Zaragoza:

BB	Murphy, Raymond. English grammar in use : a reference and practical book for intermediate students : with answers / Raymond Murphy . 1st ed., 6th print. Cambridge : Cambridge University Press, 1987
BB	Oxenden, Clive. English file : Intermediate / Clive Oxenden, Christina Latham-Koenig with Jane Hudson. 3ª ed. Oxford : Oxford University Press, 2013

Zaragoza:

BB	Murphy, Raymond. English grammar in use : a reference and practical book for intermediate students : with answers / Raymond Murphy . 1st ed., 6th print. Cambridge : Cambridge University Press, 1987
BB	Oxenden, Clive. English file : Intermediate / Clive Oxenden, Christina Latham-Koenig with Jane Hudson. 3ª ed. Oxford : Oxford University Press, 2013