Library of Congress Classification System
Q - Science
| Q | General Science. |
| QA | Mathematics, Computer Science. |
| QB | Astronomy. |
| QC | Physics. |
| QD | Chemistry. |
| QE | Geology. |
| QH | Natural History, Biology. |
| QK | Botany. |
| QL | Zoology. |
| QM | Human Anatomy. |
| QP | Physiology. |
| QR | Microbiology. |
| Q | 1-385 | General Science |
| 1-295 | General | |
| 1-4 | Periodicals | |
| 10-101 | Societies | |
| 11-33 | America | |
| 41-69 | Europe | |
| 72-83 | Asia | |
| 85-91 | Africa | |
| 93 | Australia | |
| 94 | New Zealand | |
| 99 | Pacific Islands | |
| 105 | Museums, Expositions | |
| 111 | Series of Monographs, Serial Collections | |
| 113 | Collected Works of Individual Authors | |
| 115 | Scientific Voyages and Expeditions | |
| 121 | Encyclopedias | |
| 123 | Dictionaries | |
| 124.6-127.2 | History | |
| 141-143 | Biography | |
| 151-157 | Early Works Through 1800, Including Textbooks | |
| 158 | General Works and Treatises, 1801- | |
| 160-161 | Textbooks, 1801- | |
| 162 | Popular Works | |
| 163 | Juvenile Works | |
| 164 | Recreations, Home Experiments, etc. | |
| 167 | Anecdotes, Facetiae, Satire, etc. | |
| 171 | Addresses, Essays, Lectures | |
| 172 | Special Topics | |
| 173 | Miscellany and Curiosa | |
| 174-175 | Philosophy, Methodology | |
| 179.9-180 | Research | |
| 181-183 | Study and Teaching | |
| 184-185 | Instruments and Apparatus (General) | |
| 190-197 | Audiovisual Aids in Science Teaching | |
| 199 | Handbooks, Tables, Formulas, etc. | |
| 223-227 | Communication in Science | |
| 300-390 | Cybernetics | |
| 350-390 | Information Theory | |
| QA | 1-939 | Mathematics |
| 1-43 | General | |
| 9-10.3 | Mathematical Logic | |
| 11-14 | Study and Teaching, Research | |
| 16-20 | Special Teaching Methods and Aids | |
| 21-35 | History | |
| 36-39 | General Works | |
| 40 | Handbooks, Manuals, etc. | |
| 47-59 | Tables | |
| 71-90 | Instruments and Machines | |
| 73 | Slide Rules | |
| 75-76.95 | Calculating Machines | |
| 75.5-76.95 | Electronic Computers, Computer Science | |
| 76.75-76.765 | Computer Software | |
| 99 | Miscellany and Curiosa | |
| 101-145 | Elementary Mathematics, Arithmetic | |
| 150-272.5 | Algebra | |
| 184-205 | Linear and Multilinear Algebra, Matrices | |
| 211-218 | Theory of Equations | |
| 273-274.76 | Probabilities | |
| 276-280 | Mathematical Analysis | |
| 297-299.4 | Numerical Analysis | |
| 299.6-433 | Analysis | |
| 303-316 | Calculus | |
| 319-329 | Functional Analysis | |
| 331-355 | Theory of Functions | |
| 370-387 | Differential Equations | |
| 440-699 | Geometry | |
| 451-469 | Elementary Geometry | |
| 501-521 | Descriptive Geometry | |
| 531-538 | Trigonometry | |
| 551-563 | Analytic Geometry | |
| 564-581 | Algebraic Geometry | |
| 601-608 | Transformations, Correspondences, and General Methods for Algebraic Configurations | |
| 611-614 | Topology | |
| 615-640 | Infinitesimal Geometry | |
| 641-660 | Projective Differential Geometry | |
| 801-939 | Analytic Mechanics | |
| QB | 1-991 | Astronomy |
| 1-139 | General | |
| 15-34 | History | |
| 35-36 | Biography | |
| 54 | Extraterrestrial Life | |
| 61-62 | Study and Teaching, Research | |
| 63 | Stargazers' Guides | |
| 64 | Observers' Handbooks | |
| 81-84 | Observatories | |
| 85-115 | Astronomical Instruments | |
| 140-237 | Practical and Spherical Astronomy | |
| 201 | Geodetic Astronomy | |
| 209-224 | Time | |
| 224.5-237 | Longitude and Latitude | |
| 275-343 | Geodesy | |
| 301-328 | Geodetic Surveying | |
| 330-339 | Gravity Determinations | |
| 349-421 | Theoretical Astronomy and Celestial Mechanics | |
| 414-419 | Theory of Tides | |
| 455-456 | Astrogeology | |
| 460-466 | Astrophysics (General) | |
| 468-480 | Non-Optical Methods of Astronomy | |
| 495-903 | Descriptive Astronomy | |
| 500.5-785 | Solar System | |
| 520-544 | Sun | |
| 541-544 | Solar Eclipses | |
| 611 | Mercury | |
| 621 | Venus | |
| 630-638 | Earth as Planet | |
| 641 | Mars | |
| 651 | Asteroids | |
| 661 | Jupiter | |
| 671 | Saturn | |
| 681 | Uranus | |
| 691 | Neptune | |
| 701 | Pluto | |
| 717-732 | Comets | |
| 740-753 | Meteors | |
| 754.8-792 | Meteorites | |
| 799-843 | Stars | |
| 851-855 | Clusters and Nebulae | |
| 856-903 | Galaxies | |
| 980-991 | Cosmogony, Cosmology | |
| QC | 1-999 | Physics |
| 1-75 | General | |
| 81-114 | Weights and Measures | |
| 120-168.85 | Descriptive and Experimental Mechanics | |
| 170-197 | Atomic Physics, Constitution and Properties of Matter (including molecular physics, relativity, quantum theory, and solid state physics) | |
| 221-246 | Acoustics, Sound | |
| 251-338.5 | Heat | |
| 310.15-319 | Thermodynamics | |
| 350-467 | Optics, Light | |
| 450-467 | Spectroscopy | |
| 474-496.9 | General Radiation Physics | |
| 501-766 | Electricity and Magnetism | |
| 669-675.8 | Electromagnetic Theory | |
| 676-678.6 | Radio Waves (Theory) | |
| 701-715.4 | Electric Discharge | |
| 717.6-718.8 | Plasma Physics, Ionized Gasses | |
| 750-766 | Magnetism | |
| 770-798 | Nuclear and Particle Physics, Atomic Energy, Radioactivity | |
| 793-793.5 | Elementary Particle Physics | |
| 794.95-798 | Radioactivity and Radioactive Substances | |
| 801-809 | Geophysics | |
| 811-849 | Geomagnetism | |
| 825-826 | Magnetic Surveys | |
| 830-845 | Magnetic Observations | |
| 851-999 | Meteorology, Climatology (including the earth's atmosphere) | |
| 871-874.8 | Technique, Instructions for Observers | |
| 875.5-876.7 | Meterological Instruments | |
| 878.5-879.562 | Aeronomy | |
| 879.57 | Handbooks, Tables, Formulas, etc. | |
| 879.59 | Observations, Data Summaries | |
| 879.6-879.8 | Atmospheric Chemistry | |
| 880 | Dynamic Meteorology | |
| 881-881.2 | Atmospheric Shells | |
| 882 | Atmospheric Pollutants | |
| 883-883.2 | Cosmic Relations | |
| 883.4-883.56 | Mesometeorology | |
| 883.7-883.86 | Micrometeorology | |
| 884-884.2 | Paleoclimatology | |
| 885-896 | Atmospheric Pressure | |
| 901-913.2 | Temperature and Radiation | |
| 915-929 | Aqueous Vapor | |
| 920.7-921.43 | Clouds | |
| 921.48-921.6 | Cloud Physics | |
| 924-926.2 | Rain and Rainfall | |
| 930.5-959 | Wind | |
| 940.6-959 | Storms, Cyclones | |
| 960.5-969 | Electrical Phenomena in the Atmosphere | |
| 970-972.5 | Aurora | |
| 972.6-973.8 | Radio Meteorology, Microwave Meteorology | |
| 974.5-976 | Meteorological Optics | |
| 980-999 | Climatology and Weather | |
| 982-993.7 | Geographic Divisions | |
| 993.83-994.9 | Ocean Areas, Maritime Meteorology | |
| 994.95-999 | Weather Forecasting | |
| QD | 1-999 | Chemistry |
| 1-65 | General (including alchemy) | |
| 1 | Periodicals | |
| 8-9 | Communication of Chemical Information | |
| 11-18 | History | |
| 21-22 | Biographies of Chemists | |
| 23.3-26.5 | Alchemy | |
| 40-49 | Study and Teaching, Research | |
| 51-63 | Laboratories | |
| 65 | Handbooks, Tables, Formulas, etc. | |
| 71-142 | Analytical Chemistry | |
| 81-117 | Quantitative Analysis | |
| 130-139 | Technical Analysis | |
| 146-197 | Inorganic Chemistry | |
| 161-169 | Nonmetals | |
| 171-172 | Metals | |
| 181 | Special Elements, By Chemical Symbol, A-Z | |
| 241-441 | Organic Chemistry | |
| 258-281 | Operations in Organic Chemistry | |
| 300-315 | Aliphatic Compounds | |
| 320-327 | Carbohydrates | |
| 330-341 | Aromatic Compounds | |
| 375-377 | Antibiotics | |
| 380-388 | Polymers, Macromolecules | |
| 390-395 | Condensed Benzene Rings | |
| 399-406 | Heterocyclic Chemistry and Compounds | |
| 410-412.5 | Organometallic Chemistry and Compounds | |
| 415-436 | Biochemistry | |
| 416 | Terpenes, Camphors, etc. Essential Oils | |
| 419 | Gums and Resins | |
| 421 | Alkaloids | |
| 426 | Steroids | |
| 431 | Proteins, Peptides, Amino Acids, etc. | |
| 433-436 | Nucleic Acids | |
| 450-801 | Physical and Thoretical Chemistry | |
| 462 | Quantum Chemistry | |
| 463-464 | Atomic and Molecular Weights | |
| 501-505.5 | Conditions and Laws of Chemical Reactions | |
| 506 | Surface Chemistry | |
| 510-536 | Thermochemistry | |
| 540-549 | Theory of Solution | |
| 551-562 | Electrochemistry, Electrolysis | |
| 601-607 | Radiochemistry | |
| 625-655 | Radiation Chemistry | |
| 701-731 | Photochemistry | |
| 901-999 | Crystallography | |
| 911-922 | Geometrical and Mathematical Crystallography | |
| 931-947 | Physical Properties of Crystals | |
| QE | 1-996.5 | Geology |
| 1-350.62 | General | |
| 40-48 | Study and Teaching | |
| 65-350.52 | Geographical Divisions | |
| 70.5-258 | America | |
| 72-182 | United States | |
| 185-199 | Canada | |
| 200-217 | Latin America | |
| 220-229 | West Indies, Carribbean Area | |
| 230-251 | South America | |
| 260-287.8 | Europe | |
| 289-319 | Asia | |
| 320-339 | Africa | |
| 340-349 | Australia and Pacific Region | |
| 350 | Antarctic Regions | |
| 350.2-350.22 | Atlantic Ocean | |
| 350.4-350.42 | Pacific Ocean | |
| 350.5-350.52 | Indian Ocean | |
| 351-399.2 | Mineralogy | |
| 367-369 | Determinative Mineralogy | |
| 372-387 | Descriptive Mineralogy | |
| 389-391 | Special Groups of Minerals | |
| 392-394 | Precious Stones | |
| 420-499 | Petrology | |
| 443-456.5 | Geographic Divisions | |
| 461-462 | Igneous Rocks, Volcanic Ash, Tuff, etc. | |
| 471 | Sedimentary Rocks, Sedimentology | |
| 475 | Metamorphic Rocks, Metamorphism | |
| 500-639.5 | Dynamic and Structural Geology | |
| 514-516 | Geochemistry | |
| 517 | Dynamic Geology | |
| 521-545 | Volcanoes and Earthquakes | |
| 521.5-527 | Volcanoes | |
| 531-545 | Earthquakes, Seismology | |
| 565-566 | Coral Islands and Reefs, Atolls | |
| 571-597 | Sedimentation | |
| 598-600 | Earth Movements, Mass Movements | |
| 601-613.5 | Structural Geology | |
| 640-699 | Stratigraphic Geology | |
| 654-674 | Paleozoic | |
| 675-688 | Mesozoic | |
| 690-699 | Cenozoic | |
| 701-760 | Paleontology | |
| 724-741.3 | Straigraphic Divisions | |
| 743-760 | Geographical Divisions | |
| 760.8-899 | Paleozoology | |
| 767 | Plankton | |
| 770-832 | Invertebrates | |
| 771-797 | Protozoa | |
| 798-799 | Bryozoa, Polyzoa | |
| 801-814 | Mollusca | |
| 815-832 | Arthropoda | |
| 840.5-882 | Chordata: Vertebrates | |
| 851-853 | Fishes | |
| 861-862 | Reptiles | |
| 867-868 | Amphibians, Batrachia | |
| 871-872 | Birds | |
| 881-882 | Mammals | |
| 901-996.5 | Paleobotany | |
| 914-932 | Stratigraphic Divisions | |
| 934-950 | Geographic Divisions | |
| 955-983 | Systematic Divisions | |
| QH | 1-705 | Natural History |
| 1-278.5 | General Natural History | |
| 51-58 | Study and Teaching, Research, Nature Study | |
| 75-77 | Nature Conservation, Landscape Protection | |
| 84-198 | Geographic Divisions | |
| 84-100 | Physiographic Divisions | |
| 101-198 | Topographical Divisions | |
| 201-278.5 | Microscopy | |
| 231-278.5 | Preparation and Mounting of Objects | |
| 301-705 | General Biology | |
| 324 | Methods of Research, Technique | |
| 359-425 | Evolution | |
| 426-470 | Genetics | |
| 443-450 | Recombination Mechanism | |
| 460-469 | Mutations | |
| 471-489 | Reproduction | |
| 501-531 | Life | |
| 540-549.5 | General and Animal Ecology | |
| 573-671 | Cytology | |
| 650-671 | Effect of Physical and Chemical Agents on Cells | |
| 705-705.5 | Economic Biology | |
| QK | 1-989 | Botany |
| 1-474.5 | General | |
| 91-97 | Classification | |
| 101-474 | Geographical Distribution, Phytogeography | |
| 474-495 | Spermatophyta, Phanerogams | |
| 474-493 | Trees and Shrubs | |
| 494-494.5 | Gynosperms | |
| 495 | Angiosperms | |
| 504-638 | Crytogams | |
| 509-519.5 | Local | |
| 520-532 | Pteridophyta (Ferns, etc.) | |
| 532.4-563.7 | Bryophyta, Bryology | |
| 564-580.5 | Algae, Algology | |
| 580.7-597.5 | Lichens | |
| 600-638 | Fungi | |
| 640-707 | Plant Anatomy | |
| 710-899 | Plant Physiology | |
| 746-791 | Chemical Agents Affecting Plants | |
| 861-899 | Phytochemistry | |
| 900-989 | Plant Ecology | |
| 930-938 | Physiographic Regions | |
| 980-989 | Evolution of Plants (General) | |
| QL | 1-991 | Zoology |
| 1-355 | General | |
| 61-67 | Collecting and Preserving | |
| 101-345 | Geographical Distribution | |
| 360-599.82 | Invertebrates | |
| 366-369 | Protozoa | |
| 371-374 | Porifera (Sponges) | |
| 375-379 | Coelenterata (Cnidaria) | |
| 386-394 | Worms and Other Vermiform Invertebrates | |
| 401-432 | Mollusca | |
| 434-599 | Anthropoda | |
| 605-739.8 | Chordates, Vertebrates | |
| 614-639.8 | Fishes | |
| 640-669.3 | Reptiles and Amphibians | |
| 671-699 | Birds | |
| 700-739.8 | Mammals | |
| 750-795 | Animal Behavior and Psychology | |
| 791-795 | Stories and Anecdotes | |
| 799-799.5 | Morphology | |
| 801-950.9 | Comparative Anatomy | |
| 821-827 | Skeleton, Osteology | |
| 835-841 | Vascular System | |
| 845-855 | Respiratory Organs | |
| 856-867 | Digestive Organs | |
| 872-875 | Excretory System | |
| 876-881 | Reproductive System | |
| 921-939 | Nervous System | |
| 941-943 | Integument, Skin | |
| 945-949 | Sense Organs | |
| 951-991 | Embryology | |
| QM | 1-695 | Human Anatomy |
| 1-511 | General | |
| 33.4-39 | Dissection | |
| 101-117 | The Skeleton, Osteology | |
| 131-142 | The Articulations, Joints | |
| 151-170 | Muscles | |
| 178-197 | Vascular System | |
| 251-265 | Organs of Respiration and Voice | |
| 301-367 | Organs of Digestion | |
| 368-371 | Glands | |
| 401-421 | Urinary and Reproductive Organs | |
| 451-471 | Nervous System | |
| 481-495 | Integument | |
| 501-511 | Sense Organs | |
| 531-549 | Regional Anatomy | |
| 550-577.8 | Human and Comparative Histology | |
| 601-695 | Human Embryology | |
| QP | 1-981 | Physiology |
| 1-345 | General (including influence of the environment) | |
| 34-38 | Human Physiology - General Works | |
| 39-47 | Study and Teaching, Research | |
| 81-87 | Phenomena of Animal Life (General) | |
| 88-90 | Physiology of the Tissues (General) | |
| 91-99 | Blood | |
| 101-110 | Cardiovascular System, Circulation | |
| 111-124 | Heart | |
| 141-185 | Nutrition | |
| 186-188 | Glands | |
| 190-246 | Secretions | |
| 248-250 | Urinary Organs | |
| 251-285 | Reproduction, Physiology of Sex | |
| 301-321 | Musculoskeletal System, Movements | |
| 351-495 | Neurophysiolgy, Neuropsychology | |
| 361-430 | Nervous System | |
| 431-495 | Senses, Sensation, Sense Organs | |
| 501-801 | Animal Biochemistry | |
| 519.7-519.9 | Technique | |
| 525-801 | Special Substances | |
| 531-535 | Inorganic Substances | |
| 550-801 | Organic Substances | |
| 551-619 | Proteins, Amino Acids, etc. | |
| 620-625 | Nucleic Acids | |
| 631-632 | Toxins and Antitoxins | |
| 670-671 | Pigments | |
| 701-702 | Carbohydrates | |
| 751-752 | Lipids | |
| 771-772 | Vitamins | |
| 801 | Miscellaneous Organic Substances, A-Z | |
| 901-981 | Experimental Pharmacology | |
| 911-981 | Individual Chemical Substances | |
| 915 | Aliphatic Compounds Not Containing Nitrogen | |
| 917 | Aromatic Compounds Not Containing Nitrogen | |
| 921 | Alkaloids | |
| 923 | Sugars | |
| 925 | Glycosides | |
| 931 | Resins | |
| 935 | Proteins | |
| 941 | Toxins, Venoms, Poisons | |
| 951 | Fluids and Substances Obtained from the Animal Body | |
| 971-981 | Other Organic Substances | |
| QR | 1-502 | Microbiology |
| 1-74.5 | General | |
| 75-99.5 | Bacteria | |
| 99.6-99.8 | Cyanobacteria | |
| 100-130 | Microbial Ecology | |
| 171 | Microorganisms in the Animal Body | |
| 180-189.5 | Immunology | |
| 185.8 | Immune Structures | |
| 186 | Immune Response | |
| 186.5-186.6 | Antigens | |
| 186.7-186.85 | Antibodies, Immunoglobulins | |
| 187-187.3 | Antigen-Antibody Reactions | |
| 189-189.5 | Vaccines | |
| 201 | Pathogenic Micro-Organisms, By Disease, A-Z | |
| 301-327 | Micro-Organisms of Animals | |
| 355-502 | Virology |
To the Library of Congress Classification index
