1. A theorem on involutory transformations without fixed points;Forrester, Amasa;Proc. Amer. Math. Soc.,1952
2. P. C. Hammer, Associated convex bodies, unpublished manuscript.
3. Planar line families. I;Hammer, P. C.;Proc. Amer. Math. Soc.,1953
4. P. C. Hammer, Constant breadth convex surfaces, unpublished manuscript.