For historians researching the history of exploration in North America, the publications of the Canadian Champlain Society comprise an excellent resource. Many of the Champlain Society's publications are available online through a digital collection co-sponsored by the University of Toronto Library.
According to the site,
"The collection contains eighty-three of the Champlain Society's most important volumes (over 41,000 printed pages) dealing with exploration and discovery over three centuries. It includes first-hand accounts of Samuel de Champlain's voyages in New France as well as the diary from Sir John Franklin's first land expedition to the Arctic, 1819-22."