Install The Latest EPUB Editor in Ubuntu 14.04 via PPA – UbuntuHandbook
Sigil (application) - Wikipedia
Sigil 1.9.1 - Neowin
The Lost Sigil eBook Editor Manual for epub and mobi (Kindle) formatting (v.5.3) - Kindle edition by Parrott, Suzanne Fyhrie. Reference Kindle eBooks @ Amazon.com.