500 Natural sciences & mathematics

501 Philosophy & theory

502 Miscellany

503 Dictionaries & encyclopedias

504 Not assigned or no longer used

505 Serial publications

506 Organizations & management

507 Education, research, related topics

508 Natural history

509 Historical, areas, persons treatment

510 Mathematics

511 General principles

512 Algebra & number theory

513 Arithmetic

514 Topology

515 Analysis

516 Geometry

517 Not assigned or no longer used

518 Not assigned or no longer used

519 Probabilities & applied mathematics

520 Astronomy & allied sciences

521 Celestial mechanics

522 Techniques, equipment, materials

523 Specific celestial bodies & phenomena

524 Not assigned or no longer used

525 Earth (Astronomical geography)

526 Mathematical geography

527 Celestial navigation

528 Ephemerides

529 Chronology

530 Physics

531 Classical mechanics Solid mechanics

532 Fluid mechanics Liquid mechanics

533 Gas mechanics

534 Sound & related vibrations

535 Light & paraphotic phenomena

536 Heat

537 Electricity & electronics

538 Magnetism

539 Modern physics

540 Chemistry & allied sciences

541 Physical & theoretical chemistry

542 Techniques, equipment, materials

543 Analytical chemistry

544 Qualitative analysis

545 Quantitative analysis

546 Inorganic chemistry

547 Organic chemistry

548 Crystallography

549 Mineralogy

550 Earth sciences

551 Geology, hydrology, meteorology

552 Petrology

553 Economic geology

554 Earth sciences of Europe

555 Earth sciences of Asia

556 Earth sciences of Africa

557 Earth sciences of North America

558 Earth sciences of South America

559 Earth sciences of other areas

560 Paleontology Paleozoology

561 Paleobotany

562 Fossil invertebrates

563 Fossil primitive phyla

564 Fossil Mollusca & Molluscoidea

565 Other fossil invertebrates