Falsafa-e-Dua (philosophy of supplications), by Allama Fazl Ahmad Arif. A great book that covers almost every aspect of Dua, including its philosophy, benefits, and lists many prayers of famous people.
Published by Nazir Sons Publishers. 200 pages.
Digitized by Maktabah Mujaddidiyah (www.maktabah.org) July 2012.
فلسفہ دعا، از علامہ فضل احمد عارف
Files hosted at Internet Archive (www.archive.org)