Kollmar, Herbert Max Planck Institute for Medical Research, Max Planck Society;
http://www.sciencedirect.com/science/article/pii/S0040403900997090/pdf?md5=c252876b574441292d12cec86ee4357b&pid=1-s2.0-S0040403900997090-main.pdf (beliebiger Volltext)
https://doi.org/10.1016/S0040-4039(00)99709-0 (beliebiger Volltext)
Kollmar, H. (1970). A CNDO investigation of the structures and energies of C4H+7 isomers. Tetrahedron Letters, 11(36), 3133-3136. doi:10.1016/S0040-4039(00)99709-0.
