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  • A ... A. H. Robins Company
  • A. M. Turing Award ... Aaron ben Meir
  • Aaron ben Moses ben Asher ... abaya
  • ′abāyah ... Abbott, William Alexander
  • Abbottabad ... ʿAbd Allāh II
  • ʿAbd Allāh II ibn Fayṣal ... Abdullahi dan Fodio
  • Abdülmecid I ... Aberhart, William
  • Aberhonddu ... Abiy Ahmed
  • Abiy Ahmed Ali ... About This Life
  • About Time ... Abruzzi
  • Abruzzi Apennines ... abstract
  • abstract algebra ... Abu Daoud
  • Abū Dāʾūd ... Abu Telfan, oder die Heimkehr vom Mondgebirge
  • Abu Telfan, Return from the Mountains of the Moon ... Abutilon megapotamicum
  • Abutilon pictum ... Acadia University
  • Acadian ... accelerated graphics port
  • accelerated hypertension ... Account of Reason and Faith in Relation to the Mysteries of Christianity, An
  • Account of the Foxglove, and Some of Its Medical Uses: With Practical Remarks on Dropsy and Other Diseases, An ... acervulus
  • Acestes ... Acheson process
  • Acheson, Archibald ... acidophilic organism
  • acidosis ... acorn woodpecker
  • acorn worm ... Acrocephalus scirpaceus
  • Acroceridae ... Actias luna
  • actin ... active immunization
  • active intellect ... ACV
  • ACV ... Adalbert
  • Adalbert ... Adams, Hannah
  • Adams, Harriet E. ... ADB
  • ADB ... Adélaïde du Guesclin
  • Adelaide Festival Centre ... ADF
  • ADFGVX cipher ... adjective law
  • adjoint ... Admiralty
  • Admiralty Board of the Defence Council ... Adoration of the Kings
  • Adoration of the Magi ... Adu, Helen Folasade
  • Adua ... Adventures of Eovaai, Princess of Ijaveo, The
  • Adventures of Ferdinand, Count Fathom, The ... AECMA
  • AED ... Aemilianus, Scipio
  • Aemilius Papinianus ... aeronomy
  • Aeronomy of Ice in the Mesosphere ... Aethionema grandiflorum
  • Aethionema schistosum ... affordance
  • afforestation ... African art
  • African arts ... African Queen, The
  • African Queen, The ... Afshārid Turkmen
  • Afsluitdijk ... Against the Grain
  • Against the Heathen ... Agave sisalana
  • agave subfamily ... Ageo
  • Ager Bruttius ... Aglaia
  • Aglaia ... agouti
  • Agouti ... Agrilus planipennis
  • Agrimonia ... Agulhas Negras, Pico das
  • Agulhas Plain ... Ahlgren, Ernst
  • Ahlin, Lars ... Ahn, Viktor
  • Ahnen, Die ... Aigams
  • Aiges ... air
  • air ... air-bone gap
  • air-breathing catfish ... Aisin Gioro
  • aisle ... ajnana
  • Ajo ... Akechi Mitsuhide
  • Akedah ... Akjoujt
  • Akka ... Akyab
  • Akyem ... Aladins Problem
  • Aladura ... alarm substance
  • Alarming State of the U.S. Electricity Grid, The ... Alba Longa
  • Alba Regia ... Alberoni, Julio
  • Albers, Anni ... Albertine Simonet
  • Albertinelli di Biagio di Bindo, Mariotto ... Albright, Fuller
  • Albright, Ivan ... Alces alces cameloides
  • Alces alces gigas ... Aldabra Islands
  • Aldactone A ... Alekhin, Alexander
  • Alekhine, Alexander ... Ålesund University College
  • Alethes logos ... Alexander, Fanny
  • Alexander, Francesca ... Alexis I
  • Alexis und Dora ... Alfred A. Knopf, Inc.
  • Alfred Brehm Animal House ... Algonkin
  • Algonquian ... Alias
  • Alias Grace ... Alito, Samuel Anthony, Jr.
  • Alitus ... All America Football Conference
  • All American Airways, Inc. ... All-American Soap Box Derby
  • All-Arab Feminist Union ... allegorical portraiture
  • Allegories ... Allen, Sir Hugh Percy
  • Allen, Sir James ... Allies
  • Alligator ... Allred, Gloria
  • allspice ... almond
  • almond oil ... Alosa pseudoharengus
  • Alosa sapidissima ... alpha-linolenic acid
  • alpha-oxoglutarate ... Alsace-Lorraine
  • Alsatian ... Alternate Possibilities and Moral Responsibility
  • alternating current ... Altranstädt, treaties of
  • Altria Group ... Alvaro de Castro Museum
  • Álvaro I Nimi a Lukeni ... Amagasaki
  • Amahl and the Night Visitors ... Amaral, Tarsila do
  • amaranth ... Amazing Dr. Clitterhouse, The
  • Amazing Grace ... Ambiguous Adventure
  • Ambikā-Mātā ... Amdang language
  • AMDG ... America Again: Re-becoming the Greatness We Never Weren’t
  • America and the World War ... American Board of Anesthesiology
  • American Board of Commissioners for Foreign Missions ... American Express Company
  • American Falls ... American International Group, Inc.
  • American International Pictures ... American plane tree
  • American plum weevil ... American spreading globeflower
  • American squash rackets ... AmeriCorps
  • AmeriCorps Education Award ... amidot
  • amidoth ... Amma
  • Amma’s Egg ... amoebas
  • amoebic dysentery ... Ampère’s law
  • Ampère, André-Marie ... ampulla
  • ampulla ... Amundsen, Roald Engelbregt Gravning
  • ʿAmūq ... ANA
  • Ana de Sousa ... Anakena
  • Anakin Skywalker ... Anan ben David
  • Ananas comosus ... Anas punctata
  • Anas querquedula ... Anauni
  • anautogenous fly ... Anckarsvärd, Carl Henrik, Greve
  • Anckarsvärd, Karin ... Andersen Nexø, Martin
  • Andersen’s disease ... Anderson, William R.
  • Andersontown ... Andrea da Pontedera
  • Andrea de’ Mangiabotti ... Andringitra Massif
  • Andriscus ... Anegada Passage
  • Aného ... Angel, Roger
  • Angel, Salto ... Angiosperm Phylogeny Group II
  • Angiosperm Phylogeny Group III ... Anglo-French Treaty
  • Anglo-French War in China ... Ångström, Anders Jonas
  • Angstrom, Harry ... aniline purple
  • Anilius scytale ... Anisian Stage
  • anisodactyly ... Annakin, Kenneth Cooper
  • Annála Ríoghachta Éireann ... Annie
  • Annie Allen ... Anobium punctatum
  • anode ... Anou, Chou
  • Anouilh, Jean ... Anson, George Anson, Baron
  • Anson, Pop ... anteater
  • anteating ... anthocyanin
  • anthodite ... Anthurium andraeanum
  • Anthurium scherzeranum ... anticholinergic
  • anticholinesterase ... Antilles Current
  • Antilocapra americana ... Antipholus of Syracuse
  • Antiphon ... antlion
  • Antlitz der Erde, Das ... Antwerp
  • Antwerp ... Anzac Cove
  • Anzac Day ... Apacheta Creek
  • Apáczai Csere, János ... APFSDS
  • APG II ... Apium graveolens
  • Apium graveolens rapaceum ... Apollo 11
  • Apollo 13 ... aposematic mechanism
  • aposematism ... Apparitions
  • Appaya Dikshita ... Apple Trees at Olema: New and Selected Poems, The
  • apple twig borer ... Aprilov, Vasil
  • apriorism ... Aqmola
  • AQP2 ... Aquitania
  • Aquitanian Stage ... Arabian Gulf
  • Arabian horse ... aragonite group
  • aragoto ... Arauca
  • Arauca River ... Arbroath, Declaration of
  • Arbuckle orogeny ... archaeological survey
  • archaeological timescale ... Archimedes
  • Archimedes screw ... Arctic Circle
  • Arctic Convergence ... Ardern, Jacinda Kate Laurell
  • Ardévol, José ... Arenga
  • Arenga pinnata ... Argentina
  • Argentina silus ... Argus
  • Argus ... Ariel
  • Ariel 2 ... Aristophanic comedy
  • Aristos: A Self-Portrait in Ideas, The ... Arkhangelsk
  • Arkhangelsk ... Armatrading, Joan Anita Barbara
  • armature ... armored vehicle
  • armorial achievement ... Arnauld, Antoine
  • Arnauld, Antoine ... Arnulf
  • Arnulf ... Arrabbiati
  • Arrábida Highway Bridge ... arrow
  • Arrow Cross Party ... Arsonval, Jacques-Arsìne d’
  • Arsouf, Battle of ... Art Spirit, The
  • Art Students League ... Artemisia I
  • Artemisia II ... arti
  • arti maggiori ... Artists, Society of
  • artium magister ... Arung Palakka
  • Arung Singkang ... ASA
  • Asa ... Ascaris megalocephala univalens
  • Ascaris suum ... Asellio, Gaspare
  • Asellio, Sempronius ... Asheton, Scott
  • Ashevak, Kenojuak ... Ashton, Winifred
  • Ashton-under-Lyne ... Asianic style
  • Asiatic black bear ... Asomtavruli alphabet
  • Asososca, Lake ... Aspinall, Neil
  • Aspinall, Neil Stanley ... assembly
  • assembly ... associative law
  • associative learning ... asthenia
  • asthenic personality disorder ... astrobleme
  • Astroblepidae ... asymmetrical warfare
  • Asymmetron ... Atanasoff-Berry Computer
  • Atapuerca ... Athalie
  • Athamas ... athletic type
  • athletics ... Atlantic Coast Conference
  • Atlantic Coastal Plain ... atm
  • ATM ... Atomic Scientists, Bulletin of the
  • atomic second ... Atryn
  • Atrypa ... Attic talent
  • Attica ... AUA
  • Aub, Max ... Auditorium
  • auditorium ... Augurs, Tomb of the
  • augury ... Auldjo Vase
  • Aulenti, Gaetana ... Aurigny
  • Aurillac ... Austin Friar
  • Austin High Gang ... Australian Geographic
  • Australian giant false vampire bat ... Austrian Oak, the
  • Austrian People’s Party ... Autobiography of Alice B. Toklas, The
  • Autobiography of an Ex-Colored Man, The ... automatism
  • Automatistes, Les ... auxiliary discharge converter
  • Auxiliary Manual Training Normal School ... Avebury Circle
  • Avedon, Richard ... Aveu, L’ 
  • Aveux non avenus ... Avon
  • Avon ... Awrāq ‘Iṣām ‘Abd al-‘Āṭī
  • AWRI ... Axis Pact
  • Axis porcinus ... Aylesbury
  • Aylesbury ... ʿAẓam Shah
  • Azamer be-she-vahim ... azo pigment
  • Azo Soldanus ... aʿyān
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