The first books about individual openings

[Gordon Cadden]

(a) published in the UK. The first modern book on an individual opening, may be "The Queen's Indian Defence" by Imre Konig, translated by Julius du Mont, London, Pitman,1947
(b) published in English, USA. The dutch theoretician Dr. Machgielis Euwe, commenced writing a series of individual books on the openings in 1937. The American Correspondence player, John B. Snethlage, translated the books on the QGA and QGD, and these were published in the US 1944/45, on behalf of the American Correspondence Chess League of America.

[raycollett]

When did the first books about individual openings, as opposed to general openings guides like MCO, actually start being published?

I have a copy of The Centre Game and Danish Gambit J du Mont (1920) G Bell & Sons, London. The cover states it is volume II of Chess Openings Illustrated, but I've never seen any of the others. Were they were ever printed? Unlike today's publishers Bell provides no list of prequals or sequals.

There is also Em Lasker's The Rice Gambit. My copy is 5th edition 1910, Press of Emmanuel Lasker, New York City.

In the modern era, one of the first UK single-opening monographs must be The Ruy Lopez Leonard Barden (1963) Pergamon Press Oxford.

My 1960 copy of MCO lists in its bibliography only two English language single-opening monographs: Koenig's The Queen's Indian Defence and RE Robinson's Bird's Opening.

[Alan McGowan]

A few suggestions, all in the German language.

Die Budapester Verteidigung des Damengambits, by Carl Schlechter (1918). A 16-page booklet published after the use of 1. d4 Nf6 2. c4 e5 at the Berlin 1918 tournament.
Die Skandinavische Partie, by J. Mieses (1918).
Die Aljechin-Verteidigung, by H. Fahrni (1922).
Die Englische Partie, by Hans Müller (1928).
Die Sizilianische Partie, by Albert Becker (1929).