Leach, Peter
Profile Books, 2007
Buku Teks
edited by Philip D. Sloane ... [and others]
Wolters Kluwer Health/Lippincott Williams Wilkins, 2012
Buku Teks
Leach, Robert
Routledge, 1994
Buku Teks
Leach, John, 1953-
Philadelphia Open University Press 1991,
Buku Teks
Goode, William J.
Prentice-Hall, 1964
Buku Teks