Archaeology 1,135 Asian history 978 Anthropology 877 Ancient history: to c 500 CE 655 Architecture 512 Architectural structure & design 475 Artificial intelligence 442 Art techniques & principles 399 Applied ecology 396 African history 318 Agricultural science 279 Australasian & Pacific history 272 Agriculture & farming 252 Adult education, continuous learning 211 Archaeology by period / region 172 Automatic control engineering 144 Agronomy & crop production 141 Alternative & renewable energy sources & technology 137 Applied mathematics 121 Algorithms & data structures 119 Australia 117 Astronomy, space & time 109 Ancient religions & mythologies 104 Age groups: children 94 Analytical chemistry 91 Automotive technology & trades 89 Agriculture & related industries 86 Archiving, preservation & digitisation 82 Anthologies (non-poetry) 78 Animals & society 67 Agricultural economics 66 Accounting 65 Aerospace & aviation technology 63 Advertising & society 61 Age groups: the elderly 59 Architecture: professional practice 59 Africa 58 Arbitration, mediation & alternative dispute resolution 57 Art forms 48 Acoustic & sound engineering 46 Astronautics 44 Algebra 43 Air forces & warfare 41 Archaeological science, methodology & techniques 40 Antiques & collectables: books, manuscripts, ephemera & printed matter 38 Atomic & molecular physics 38 Abnormal psychology 37 Antiques & collectables 37 Applied physics 35 Armed conflict 34 Arms negotiation & control 33 Age groups: adolescents 32 Autism & Asperger's Syndrome 32 Animal husbandry 30 Argentina 29 Austria 28 Accident & emergency medicine 27 Applied optics 27 Aquaculture & fish-farming: practice & techniques 27 Asia 27 Advice on careers & achieving success 26 Art & design styles: from c 1960 26 Art treatments & subjects 24 Animated films 23 Archaeological theory 23 Art styles not defined by date 23 Accounting: study & revision guides 22 Animal ecology 22 Austro-Hungarian Empire 22 Acting techniques 21 Ambulance & rescue services 21 Anatomy 21 Art & design styles: c 1900 to c 1960 20 Animal behaviour 19 Agricultural engineering & machinery 18 Anarchism 17 Astrophysics 17 Aerodynamics 16 Art: financial aspects 16 Aspects of religion (non-Christian) 16 Aircraft: general interest 15 Adventure 14 Animals & nature in art (still life, landscapes & seascapes, etc) 14 Age groups 13 Allergies 13 Anaesthetics 13 Analytical philosophy & Logical Positivism 13 Ancient Rome 13 Animal physiology 13 Art of indigenous peoples 13 Audiology & otology 13 Autobiography: historical, political & military 13 Agricultural law 12 Ancient (Classical) Greek 12 Art & design styles: Baroque 12 Australasia 12 Australian Aboriginal languages 12 Animal reproduction 11 Advice on parenting 10 Analytical & Jungian psychology 10