1. Archbald H (1922) The four hour day in coal. H.W. Wilson Company, New York
2. Bailey GL (1991) The Commissioner of Labor's Strikes and Lockouts: a cautionary note. Labor History 32(3):432–440
3. Birdsall WC (1953) The problem of structure in the Knights of labor. Ind Labor Relat Rev 6(4):532–546
4. Bituminous Operators' Special Committee (1923) Comparative efficiency of labor in the bituminous coal industry under union and nonunion operation, a brief submitted to the United States Coal Commission. September 10, 1923
5. Blanchflower DG, Bryson A (2007) What effect do unions have on wages now and would freeman and Medoff be surprised? In: Kaufman BE, Bennett JT (eds) What do unions do? A twenty-year perspective. Transaction Publishers, New Brunswick, pp 79–113