HMS H21 (English Wikipedia)

Analysis of information sources in references of the Wikipedia article "HMS H21" in English language version.

refsWebsite

Global rank English rank

1books.google.com

3^rd place

3^rd place

1naval-history.net

5,452^nd place

3,749^th place

low place

low place

books.google.com

Derek Walters (2004). The History of the British 'U' Class Submarine. Casemate Publishers. pp. 2–. ISBN 978-1-84415-131-8.

gwpda.org

J. D. Perkins (1999). "Building History and Technical Details for Canadian CC-Boats and the Original H-CLASS". Electric Boat Company Holland Patent Submarines. Retrieved 20 August 2015.

naval-history.net

Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8. Retrieved from Naval-History on 20 August 2015.