Bruquetas, Rocio (2007), p. 442
Matteini, Mauro; Moles, Arcangelo (2001), p. 82
Calvo, Ana (2003), p. 28
Asensio Fuentes, Antonio (1982), p. 31
Cardon, Dominique (2003), p. 385
Roquero, Ana; Córdoba, Carmen (1981), pp. 44-46
Perego, François (2005), pp. 323-327
Eastaugh, Nicholas (2004), p. 283
Alfaro Giner, Carmen (1984), p. 202
Pedrola, Antoni (1998), pp. 93-94
Carreras Matas, Luis (1982), p. 20