Artillery training : Employment and organization of the Air O.P. / War Office. Vol I. General Tactical Employment - Engeland Voorschrift, 26/GS Publications/921 Artillery training : Deployment of an air O.P. Squadron / War Office. Vol II - Engeland Voorschrift, 26/GS Publications/1203 Artillery training : Employment and organization of the Air O.P. / War Office. Vol I. General Tactical Employment - Engeland Voorschrift, 26/GS Publications/1233
