Marina Tosic Dragana S. Cvetkovic-Ilic Invertibility of a linear combination of two matrices and partial orderings. 4651-4657 2012 218 Appl. Math. Comput. 9 https://doi.org/10.1016/j.amc.2011.10.052 db/journals/amc/amc218.html#TosicC12