1. 1. D.W. Moodie, and A.J.W. Catchpole Environmental Data from Historical Documents by Content Analysis: Freeze-up and Break-up of Estuaries on Hudson Bay 1714-1871 (Manitoba Geographical Studies 5, Dept. of Geography, University of Manitoba, Winnipeg, 1975). This monograph provides a general discussion of content analysis as a tool for extracting environmental data from historical accounts, and affords a step-by-step application of the method to historical descriptions of freeze-up and break-up.
2. 2. I. de S. Pool Trends in Content Analysis (University of Illinois Press, Urbana, 1959), p.196 .
3. 3. W.T.R. Allen Break-up and Freeze-up Dates in Canada (Canada, Department of Transport, Meteorological Branch, CIR-4116, ICE-17, 1964), p.5 .
4. 4. A.J.W. Catchpole, and D.W. Moodie "Changes in the Canadian Definitions of Break-up and Freeze-up," Atmosphere, 12 (1974 ), 133 -8 .
5. 5. F.E. Burbidge, and J.R. Lauder A Preliminary Investigation into Break-up and Freeze-up Conditions in Canada (Canada, Department of Transport, Meteorological Branch, CIR-2939, TEC-252, 1957), p.1 .