Three Strikes: Labor's Heartland Losses and What They Mean for Working Americans By Stephen Franklin. Guilford Press, 308 pages, $23.95 Three Strikes: Miners, Musicians, Salesgirls, and the Fighting Spirit of Labor's Last Century By Howard Zinn, Dana Frank, and Robin D.G. Kelley. Beacon Press, 174 pages, $23.00 From the Folks Who Brought You the Weekend: A Short, Illustrated History of Labor in the United States By Priscilla Murolo and A.B. Chitty. The New Press, 364 pages, $27.50 S omeday, when our own time is a distant memory, scholars will blow the dust off the 1935 Wagner Act, the enabling legislation for the American labor upheavals of the 1930s and 1940s, and stare blankly at some long-lost language that doesn't jibe with the pattern of history. The act promised to correct a host of imbalances and injustices by "encouraging the practice and procedure of collective bargaining and by protecting the exercise by workers of full freedom of association, self-organization, and...