However, there is a recent publication from Kew that gives a comprehensive listing of all currently recognised species, together with synonyms, literature references and distributions by country and state or province. Authors: Gevaerts, R & Frodin, D G; title: World checklist and bibliography of Fagales (Betulaceae, Corylaceae, Fagaceae and Ticodendraceae). If your interest is in oaks of the whole world, this is a good start. My copy cost the Australian equivalent of about $45.