Hu, Xiao-Chun, et al. “Synthesis and Crystal Structure of Ni(II) Complex With 3-Hydroxyadamantane-1-Carboxylic Acid and 4,4’-Bipyridine”. Asian Journal of Chemistry, vol. 23, no. 2, Oct. 2010, pp. 713-6, https://asianpubs.org/index.php/ajchem/article/view/15816.