Chess had a golden era when The King’s Gambit was the favorite opening of every attacking player. In the glory days of Paul Morphy it was considered almost cowardly to play anything else. Legends such as Spassky and Bronstein kept the flame burning in the 20th century, but its popularity faded as players became distrustful of White’s ultra-aggressive approach. Nevertheless there are honorable exceptions whose games prove that this ancient weapon can still draw blood – Short, Nakamura and Zvjaginsev are world-class players who have used the King’s Gambit successfully. In this groundbreaking work, grandmaster John Shaw shows that the ultimate Romantic chess opening remains relevant and dangerous even in the computer era.
I don't see how you could consider playing the King's Gambit in this computer age without Shaw's book to guide you. He goes through every line and debunks many of the previously held opinions about what works and what doesn't. He's uncompromising, too, with his play at your peril pronouncements. I have at least 50 bookmarks in this book and have used it to plan opening play in at least a couple hundred games. Great resource that has made this fun opening still playable.
The big questions are 1) who can write a 680 page book on one opening and 2) how the hell am I going to finish it ? Well there is a lot of history and ways to accept and decline it . Shaw offers a book on a topic that he is passionate about, well researched and delivered with humor and in a way that feels like is speaking to you directly. I have played the King's Gambit as white and play Bc4 and 0-0; many of the lines that Shaw recommend plays Nc3 and g3 which are new KG ideas for me.
This is the G.O.A.T. (Greatest of All Time) of opening books, plus it's on what is probably the most exciting and most romantic opening. Can't beat it! The only shortcoming is that Shaw recommends 4.Nc3 (instead of 4. h4 or 4.d4) after 3.g5, which gives black the better game in this one particular move order: