Collins English dictionary : plus good writing guide
Harper Collins Publishers, 2003
 Buku Referensi
Collins English spelling dictionary
HarperCollins Publishers, 1993
 Buku Referensi
Collins COBUILD English dictionary
editor in chief, John Sinclair
HarperCollins Publishers, 1995
 Buku Referensi
Collins today's English dictionary
HarperCollin Publishers, 1995
 Buku Referensi
Kamm, Antony
Collins biographical dictionary of English literature
Harper Collins Pub., 1993
 Buku Referensi