search for Petch's classic paper entitled "The cleavage strength of polycrystals"
Recently, I am reading several classic works on crystal plasticity. But, it seems to be difficult for me to obtain several very old papers in this area. For example, one of the classic papers on Hall-Petch relation,
Petch, N.J., The cleavage strength of polycrystals. The Iron and Steel Institute, 1953, 174: 25-28. I have tried many ways to get the original paper, but I finally failed. Could someone please send me a copy of this paper? Thanks a lot. Here is my email: dbliu2009 [at] gmail.com