"Teddy Suhren; Ace of Aces: Memoirs of a U-Boat Rebel"

[John Pancoast]

Though I'm not a fan of memoirs for various reasons, this is a good read.

Some interesting parts:

- "We never attacked underwater by night; the attack periscope simply didn't gather enough light." (No mention of the observation scope being used for attacking at all)

- "It is vital to keep the boat absolutely still at the moment of making observations; it mustn't move at all, otherwise the angle will vary."