Section 15.1 History
This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu/
Euler circuits were named after Leonhard Euler (pronounced "Oiler". You might
wish to check out this interesting and important person in the history of
mathematics.
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Euler.html
Hamiltonian cycles are named after William Rowan Hamilton:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Hamilton.html
Klein bottles (Problem 60) are named after Felix Klein:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Klein.html