Altmann, M., Enkelmann, V., Beer, F., & Bunz, U. H. F. (1996). Synthesis of linear oligomers of [1,3-diethynyl-2,4-bis(trimethylsilyl)cyclobutadiene]cyclopentadienylcob alt: Dimer to nonamer. Organometallics, 15(1), 394-399. doi:10.1021/om950652+.