The Stanford Encyclopedia of Philosophy is a dynamic, online scholarly encyclopedia in which entries are kept up to date by an expert or groups of experts in the field.
The Oxford Dictionary of Philosophy by 
The Oxford Companion to Philosophy by 
The Oxford Companion to the Mind by 
New Dictionary of the History of Ideas by 
The Cambridge Dictionary of Philosophy, 2nd ed. by 
Encyclopedia of Philosophy and the Social Sciences by 
Encyclopedia of Aesthetics by 
Oxford Companion to Consciousness by Print reference books are located on the first floor of Collins Library.
Encyclopedia of Asian Philosophy by 
Encyclopedia of Ethics by 
A Companion to Environmental Philosophy by 
The Oxford Handbook of Aesthetics by The Cambridge Histories series is an indispensable reference collection with over 300 titles spanning 15 subject areas, including philosophy. Each (often multi-volume) history provides a big-picture perspective of its subject, introduces readers to existing scholarship, and proposes new trends in the field. Below are some representative examples.
The Cambridge History of Philosophy in Late Antiquity by 
The Cambridge History of Later Greek and Early Medieval Philosophy by 
The Cambridge History of Renaissance Philosophy by 
The Cambridge History of Seventeenth-Century Philosophy by 
The Cambridge History of Eighteenth-Century Philosophy by 
The Cambridge History of Philosophy in the Nineteenth Century (1790-1870) by 
The Cambridge History of Philosophy, 1945-2015 by 
The Oxford Handbook of Philosophical Methodology by 
The Cambridge Companion to Philosophical Methodology by 
Advances in Experimental Philosophy and Philosophical Methodology by 