I used V. D. Mahajan for the most part. Along with it, I also studied David Thomson. But I think VDM is enough for 80% of the topics. For a few topics (~20%), D. Thom. is a better choice. Lastly, I made ample use of internet. And with the change in syllabus, recent historical developments (post-1960) will have to be covered from the internet as well, or some new book.