Minutes and papers pertaining to the First and Second Conferences of Latvian Envoys Abroad, Riga 1923 June 18 and 1935, June 28 -July 3,
Top Secret and personal memoranda of M. Valters to the Deputy Prime Minister and Minister of War of Latvia, General Janis Balodis. Published as Mana sarakste ar Karli Ulmani un Vilhelmu Muntery: Latvijas tragiskajos gados. Stockholm, Jaune Latvija 1957