Ética nicomáquea
The "Nicomachean Ethics" is very often abbreviated "NE", or "EN", and books and chapters are generally referred to by Roman and Arabic numerals, respectively, along with corresponding Bekker numbers. (Thus, "NE II.2, 1103b1" means ""Nicomachean Ethics", book II, chapter 2, Bekker page 1103, Bekker column b, line number 1".)