Deutsches U Boot, U 402, Unterseeboot im Trockenen | xl
Uboot-Recherche. U-402 402_07(23.02.43-26.05.43)
U-402 under Siegfried Freiherr von Forstner patrolled New England 4 days in April 1942 - his brother was a U-Boat commander also - Eric Wiberg
uboat.net - Articles
Sunken missing Indonesian submarine found cracked open | The Japan Times
Amazon.com: Knight of the North Atlantic: Baron Siegfried von Forstner and the War Patrols of U-402, 1941-1943: 9781399096768: Hamilton USAR, Aaron S: Books
THE VICTORIOUS CAMPAIGNS OF THE U-402 MODEL CONSTRUCTION