This older dataset covers the years 1970-1997, and is constructed by Statistics Canada, who also used the United Nations trade data.
The Statistics Canada world trade was purchased and distributed by the NBER under a grant from the National Science Foundation, as described in:
Feenstra, Robert C., Robert E. Lipsey and Harry P. Bowen, 1997, "World Trade Flows, 1970-1992, with Production and Tariff Data," NBER Working Paper 5910.