Based on [LY].

- [LY]:

   Lex & Yacc
   by H. Altay G{\"u}venir
   http://www.cs.bilkent.edu.tr/~guvenir/courses/CS315/lex-yacc/index.html
   http://www.cs.bilkent.edu.tr/~guvenir/courses/CS315/lex-yacc/lex-yacc.pdf