Reference resources are a great place to begin your research. They can help you define terms as well as to find basic information about a topic, a chronicle of its history, theories, key people and sometimes a bibliography of additional sources.
There are many different types of reference sources, which include dictionaries, encyclopedias, thesauri, bibliographies, handbooks, maps, style manuals to name a few.
Oxford Reference Online - History
Access to a collection of over 100 dictionary, language reference, and subject reference works. Featured titles include:
The Routledge Companion to Historical Studies
An introduction to the key issues, historians and philosophers and their ideas and theories.
Dictionary of Historic Documents
REF D9 .D525 2003
Guide to significant documents of the world from ancient times to the present.
Oxford Bibliographies offers peer-reviewed annotated bibliographies which will help you to narrow the vast number of citations to the best scholarship on a given topic.
Bibliographies are browseable by subject area and keyword searchable.
For example, there are research guides on African Studies, Atlantic history, Islamic Studies, Medieval Studies, to name a few.
Oxford Atlas of World History
G1030 .P57 1999b m (SL Maps & Air Photos)