Intermeshing-rotor helicopter (English Wikipedia)

Analysis of information sources in references of the Wikipedia article "Intermeshing-rotor helicopter" in English language version.

refsWebsite

Global rank English rank

1books.google.com

3^rd place

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low place

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books.google.com

Day & McNeil; Lance Day; Ian McNeil (1998). Biographical Dictionary of the History of Technology. Taylor & Francis. p. 261. ISBN 0-415-19399-0.

suasnews.com

Mortimer, Gary (13 October 2017). "Swissdrones testing heavy lift helicopter". sUASNews.com. Retrieved 16 October 2017.