Analysis of information sources in references of the Wikipedia article "Leonhard Euler" in English language version.
Higgins, Peter M. (2007). Nets, Puzzles, and Postmen: An Exploration of Mathematical Connections. Oxford University Press. p. 43. ISBN 978-0-19-921842-4.
Higgins, Peter M. (2007). Nets, Puzzles, and Postmen: An Exploration of Mathematical Connections. Oxford University Press. p. 43. ISBN 978-0-19-921842-4.
Higgins, Peter M. (2007). Nets, Puzzles, and Postmen: An Exploration of Mathematical Connections. Oxford University Press. p. 43. ISBN 978-0-19-921842-4.