Fluid Dynamic Drag by Horner is a solid aero book, but raises the question "what are you looking for?"
If your primary objective is to understand the basics of drag and how to estimate parasite drag components 'the way they done it back then', it is hard to beat and you don't need higher math or solve differential equations. Chapter 14 is a great walkthrough on steps to convert top speed at a specific altitude for a given Hp engine to derive flat plate drag for a Bf 109G - for example - then reverse engineer parasite drag for individual fuselage groups.
If you want to see 'real life aero Performance estimation processes, given wind tunnel data for a specific Speed/RN, then I recommend the NAA reports NA-5534 for P-51B-1-NA and NA-8449 for P-51D-5-NA. You MUST have some substantial aero academics to bring with you as several steps in the process assume that you 'know the obvious'. The P-51D report is buried in the Smithsonian folder labeled MISC, and further imbedded in the P-51D-5 Wing Structural analysis Report (500+ pages). he P-51B report is available at Aero Library.
If you are looking for Fundamentals of Aero/performance there are many more to be recommended