• 520 - Astronomy & allied sciences
  • 797 - Aquatic & air sports
  • 953 - Arabian Peninsula & adjacent areas
  • 998 - Arctic islands & Antarctica
  • 022 - Administration of physical plant
  • 158 - Applied psychology
  • 168 - Argument & persuasion
  • 169 - Analogy
  • 180 - Ancient, medieval & eastern philosophy
  • 185 - Aristotelian philosophy
  • 229 - Apocrypha & pseudepigrapha
  • 239 - Apologetics & polemics
  • 267 - Associations for religious work
  • 283 - Anglican churches
  • 354 - Administration of economy & environment
  • 358 - Air & other specialized forces
  • 366 - Associations
  • 374 - Adult education
  • 494 - Altaic, Uralic, Hyperborean & Dravidian
  • 496 - African languages
  • 499 - Austronesian & other languages
  • 512 - Algebra
  • 513 - Arithmetic
  • 515 - Analysis
  • 543 - Analytical chemistry
  • 590 - Animals (Zoology)
  • 595 - Arthropods
  • 621 - Applied physics
  • 630 - Agriculture & related technologies
  • 636 - Animal husbandry
  • 657 - Accounting
  • 659 - Advertising & public relations
  • 692 - Auxiliary construction practices
  • 711 - Area planning
  • 720 - Architecture
  • 721 - Architectural structure
  • 722 - Architecture to ca. 300
  • 723 - Architecture from ca. 300 to 1399
  • 724 - Architecture from 1400
  • 739 - Art metalwork
  • 796 - Athletic & outdoor sports & games
  • 810 - American literature in English
  • 811 - American poetry in English
  • 812 - American drama in English
  • 813 - American fiction in English
  • 814 - American essays in English
  • 815 - American speeches in English
  • 816 - American letters in English
  • 817 - American humor & satire in English
  • 818 - American miscellaneous writings