The Oxford Atlas of Exploration. Oxford University Press, 1998. Illustrated chronicle of humanity's exploration of the unknown; covers all geographic regions.
Baker, Daniel B., ed.Explorers and Discoverers of the World. Gale Research, 1993. Profiles of more than 300 explorers, from ancient times to the recent past.
Bohlander, Richard E., ed.World Explorers and Discoverers. Macmillan, Reprint Da Capo, 1991. 1998. Solid coverage of the explorers and others who supported exploration.