Yang, Xiu-Yun, et al. “Synthesis and Characterization of 4,4’-Di(p-Aminophenylethynyl)-6,6’-bis(N,N-bis(t-butoxycarbonylmethyl)amino Methyl)-2,2’-Bipyridine”. Asian Journal of Chemistry, vol. 26, no. 8, Apr. 2014, pp. 2256-8, doi:10.14233/ajchem.2014.15686.