1973 was the first year that an official Yearbook was produced by the Redskins. I have never seen examples from 1975, nor 1978 through 1982. I have had several site visitors email me stating they have never seen any from those years either, so the assumption is that they were never produced those years. The team has put out a yearbook continuously since 1983. I will eventually scan the covers of the post-1992 yearbooks as well for completeness.
The Sports Focus Issues were produced by a company in Wisconsin. The earliest example I've seen is a 1968 Green Bay Packers Sports Focus Yearbook. Initially focused on producing Packers yearbooks, it was not until 1973 that the company started producing additional versions for five additional teams: The Redskins, Chicago Bears, Detroit Lions, Minnesota Vikings, and New York Giants.