Rajnish, Kumar, and Vandana Bhattacherjee. “Class Inheritance Metrics-An Analytical and Empirical Approach”. INFOCOMP Journal of Computer Science, vol. 7, no. 3, Sept. 2008, pp. 25-34, https://infocomp.dcc.ufla.br/index.php/infocomp/article/view/226.