Academic Search Complete is a database of academic journals, magazines, and other scholarly resources, covering a wide range of subjects across the humanities, sciences, and social sciences. It's a great starting point for research, especially with its inclusion of many open access publications.
JSTOR provides comprehensive access to peer-reviewed scholarly journals, books, and primary sources from various disciplines within the humanities and social sciences.

Concise Atlas of World
Andromeda Encyclopedic Dictionary of World History
Chambers Dictionary of World History
Encyclopedia of World History