Y. Sinelnikove, Rubinstein, A. , Srebnik, M. , and Quntar, A.A.A.A. . 2009. “Direct Formation Of Cyclobutenylphosphonates From 1-Alkynylphosphonates And Cp2Zrcl2/2Etmgcl/2Cucl”. Tetrahedron Letters, 50, 8, Pp. 867-869.