The Neptun-class submarine was a Swedish submarine class built by Kockums. The first submarine was launched in 1942 and a total of three submarines were built: HSwMS Neptun, HSwMS Najad and HSwMS Nacken. The class was decommissioned in 1966.[1][2]
Blackman, Raymond V.B. (1960). Jane's Fighting Ships 1960–61. London: Sampson Low, Marston & Co., Ltd.
Westerlund, Karl-Eric (1980). "Sweden". In Chesneau, Roger (ed.). Conway's All the World's Fighting Ships 1922–1946. New York: Mayflower Books. pp. 368–377. ISBN0-8317-0303-2.