Enrico Fermi and C.N. Yang, "Are Mesons Elementary Particles?", in the Physical Review, December 15, 1949, American Institute of Physics, Volume 76, No. 12, Pp. 1739-1744 [in the entire issue, pp. 1739-1934, iii-xv], in the original wrappers. A fine copy. $350
- Yang (another paper by whom appears elsewhere in this blog) received his Nobel in 1957 for his work on parity nonconservation of weak interaction and was at this writing an assistant to Fermi, in which they discusses whether mesons--subatomic particles composed of one quark and one antiquark--are elementary particles.