Education/academic and ELT
Oxford Classical Dictionary edited by Simon Hornblower, Antony Spawforth and Esther Eidinow (Hardcover, Oxford University Press, 4th edn, 2012)
Useful when tackling classics topics, particularly for its list of abbreviations for classical texts, which are fairly standardly used across the discipline. Access available online through Oxford Reference.
Classics style sheets regularly refer to L'Année Philologique for journal abbreviations. This can be found by subscription at L'Année philologique on the Internet, a database published by the Société Internationale de Bibliographie Classique in collaboration with the Society for Classical Studies.