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The O 12-class submarine consisted of four submarines built for the Royal Netherlands Navy. The ships, with a diving depth of 60 metres (200 ft), were used for patrols in the Dutch home waters. The class comprised O 12, O 13, O 14 and O 15. O 12 entered German service in 1943 as UD-2.
Jalhay, P.C.; Wijn, J.J.A. (1997). Ik nader ongezien! De onderzeeboten van de Koninklijke Marine [I'm Approaching Unseen! The submarines of the Royal Netherlands Navy] (in Dutch). Amsterdam: De Bataafsche Leeuw. ISBN978-90-6707-462-9.