Reference sources like these will guide you through the recent scholarly thinking on a topic and then point you to related primary and secondary sources.
Regularly updated annotated bibliographies. University of Chicago Library subscribes to many sections of Oxford Bibliographies Online such as African Studies, Anthropology, Art History, Atlantic History, Buddhism, Childhood Studies, Chinese Studies, Cinema and Media Studies, Classics, Environmental Science, Geography, International Law, International Relations, Islamic Studies, Latin American Studies, Medieval Studies, Military History, Music, Political Science, Renaissance and Reformation, Social Work, and Sociology.
The best modern art encyclopedia, searchable by concepts as well as by artists' names. The bibliographies are a worthwhile starting point for further research