Footnotes are tricky. My general practice is to do as you have suggested, and put them at the end of the chapter—this seems to be the best general purpose solution. If you are targeting specific reading systems/devices, you can get more fancy: on the iPad, for example, you can use pop-up footnotes, as detailed in the answers to [this question][1].

Another option is to include the footnotes inline in the main body text, perhaps set off from the main body text with horizontal rules and even a different font. This is clearly not ideal for reference footnotes, but for the sample you've included, it could be a totally reasonable way to go, and would work across all epub reading systems.


  [1]: http://ebooks.stackexchange.com/questions/5966/footnote-as-popup-in-epub