A. Ghosh, A. K. Das, R. K. Biswas, B. Ghosh, A. Pal, and S. Ghosh, “Is there any difference in efficacy of oral sildenafil therapy in primary vs secondary Pulmonary Arterial Hypertension?”, J. Drug Delivery Ther., vol. 3, no. 1, Jan. 2013, doi: 10.22270/jddt.v3i1.375.