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