@ Sana Rafique
Well, preparing for CSS we do not rely upon a single book in any subject however comprehensive.
I suggest you better look into the syllabus for Economics, prepare the topics give there in details and the tools or theories of Economics discussed or used in those topics should be covered too. Further, for current economic trends or issues, do read pink pages of Monday Dawn. These are all on economic issues. Do know the growth rates and trends of the economies of many nations.
I have studied Economics for four whole years in my BSc Honors, and before that I had an FSc Pre-medical. So all I knew about Economics was in the last four years. I think you have also studied Economics already. So we should go with the option that we are well familiar with.
Do share if any body gets any problem regarding Economics. I shall be pleased to help you out.

Regards,
Imran Saifi

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“Those who danced were thought to be quite insane by those who could not hear the music.”