Rukhsana Firdous , Safia Ahmed,Shabbir Ahmad Chaudhary , Ahsan Ahmad ,Naeem Akhtar. 2011. “Evaluation of Resistance in Clinical Isolates of E. Coli, S. Aureus, and P. Aeruginosa Against β-Lactam Antibiotics and Gentamicin”. Journal of Rawalpindi Medical College 15 (1). http://journalrmc.com/index.php/JRMC/article/view/637.