I did my O levels back in 2002 and studied from Ikram rabbani's book for it. I remember it being good with precise. However, I dont have the book anymore. My brother is currently doing his O levels and have two history books by Nigel Kelly and Nigel Oscar. The syllabus for CSS Pak Affairs seem to be consistent with that of O Levels. Do you think that it'll be sufficient to consult the Nigel books only?