JEAN-YVES JOUANNAIS : ENCYCLOPAEDIA OF WAR

Entry:"Chin strap", excerpt: "The personnel required for visits to stations, visits to hospitals and prisons, and for the rounds, are provided by the corps. Uniform — visits are carried out in day uniforms with a chin strap."

Guide Fournier: 1916-1917, à l’usage de MM. les officiers de toutes armes et de tous services, 8th year (10th edition), published by L. Fournier, Paris, 1917, p. 72