S. ZEB, and M. YOUSAF. “Numerical Solution of Symmetric Saddle Point Problems by Updating Procedure Using QR Householder Factorization”. Sindh University Research Journal - SURJ (Science Series), vol. 48, no. 3, Sept. 2016, https://sujo.usindh.edu.pk/index.php/SURJ/article/view/5009.