Neugebauer, Franz A. Department of Organic Chemistry, Max Planck Institute for Medical Research, Max Planck Society;
http://www.sciencedirect.com/science/article/pii/S0040403900897592/pdf?md5=a9125ffc428737bd88d73c051ad43559&pid=1-s2.0-S0040403900897592-main.pdf (Any fulltext)
https://doi.org/10.1016/S0040-4039(00)89759-2 (Any fulltext)
Neugebauer, F. A. (1968). The constitution of the radical intermediate between formazan and tetrazoliumsalt. Tetrahedron Letters, 7(17), 2129-2132. doi:10.1016/S0040-4039(00)89759-2.