CSS is not a one-book examination. Gone are the days when candidates were required merely to write short notes on topics like "Two Nation Theory". Now they require a critical appraisal of it.
This requires preparation of a topic from its various possible angles.
PA paper consists of three parts: objectives+history+current
My posted objectives of PA will really help but still more study is required.
All the historical dates should be noted in a note book that you encounter during your study.

History section consists of actual facts of an event + a critical analysis or other important aspect of it. The bare facts of a historical event can be found in any book of Pakistan Studies. However, to cover critical analysis of a historical topics you need to study:
1) Newspapers articles revisiting important historical events.
2) Any magazine published by Pakistan Studies department of any university. Good analysis of historical events from various possible angles is contained by these magazines.

Lastly, current PA can be covered from editorial+opinions of various newspapers.
The Frontier Post is ideal one. However, current material with facts and figures can be found in Dawn, The News.
Current PA study should be done on the pattern of CA. At least six month newspapers should come under your study. The subject recurring in news articles becomes the important topic.


Try to get JOURNAL OF THE PAKISTAN HISTORICAL SOCIETY. Also get its previous issues too.