[Gerald]

https://www.amazon.co.uk/U-boat-War-.../dp/1861762879
https://www.crookwellgazette.com.au/...son-crookwell/
https://www.casematepublishers.com/d...l#.XzKNnigzZEY
https://www.naval-military-press.com...diary-of-u564/
https://www.britannica.com/topic/con...val-operations
https://www.history.navy.mil/content...c-convoys.html
http://www.usmm.org/ww2.html
https://www.veterans.gc.ca/eng/remem...heets/atlantic
https://www.veterans.gc.ca/eng/remem...heets/murmansk
https://www.rmg.co.uk/discover/resea...-world-war-two
https://www.nationalarchives.gov.uk/...rds-1939-1945/
http://www.convoyweb.org.uk/
https://www.rbth.com/defence/2016/03...st-hour_575559
https://www.bbc.co.uk/history/ww2peo...icleId=6652091
https://www.wilsoncenter.org/event/t...e-russian-view
https://nzhistory.govt.nz/war/the-me...f-the-atlantic
https://www.google.com/search?sa=N&s...w=1536&bih=711
https://www.konditori100.se/SiWW2/sww2st.htm
https://www.marinersmuseum.org/sites...tlantic/aa.htm
https://apps.dtic.mil/dtic/tr/fulltext/u2/a183840.pdf
https://en.wikipedia.org/wiki/Order_...r_Convoy_PQ_17
https://www.nationalww2museum.org/wa...e-convoy-pq-17

A few links...But as you already know, there are many different books and links on the subject.