Cover image not available
"Top secret U -- Most secret source -- MSS Ultra CS"--Cover illustration of original classification, now declassified.
PQ 17 convoy disaster
Sinking of the Scharnhorst
Hunting the Tirpitz.
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Ultra's Arctic war by John Jackson. ISBN 9780854202294. Published by Military Press. in 2003. Publication and catalogue information, links to buy online and reader comments.