M. Rani, D. Kumar Shukla, and A. Ali Khan, “One Pot Synthesis of 3,9-Bis-(2,4-di-tert-butyl phenoxy)-2,4,8,10-tetraoxa-3,9-diphospha-spiro[5.5]undecane, their Chalcogenides and Metal Complexes”, ajc, vol. 25, no. 8, pp. 4556–4558, Mar. 2013.