Ntirlis: Playing 1. E4 E5 - A Classical Repertoire Damen Gambit International Master John Watson is

International Master John Watson is a former US National High School Championship champion

A series of exercises at the end of the book allows you to check that you have grasped the main points

Concentrates on the fundamental principles of the openings

Anand: World Chess Champion - An Appreciation by Sean Marsh

then this book is a perfect place to start

Ntirlis: Playing 1. E4 E5 - A Classical Repertoire Damen Gambit International Master John Watson isBuild a Solid 1 e5 Repertoire Against 1. e4 Playing 1. e4 e5 by Nikolaos Ntirlis offers a practical guide to meeting 1. e4 with Black's most classical response. Rather than forcing players to memorise endless variations, this repertoire book prioritises sound positional understanding and reliable defensive structures. The focus is on concrete, computer tested systems that work at multiple playing levelsfrom ambitious amateurs to experienced