Stewart, Jon, author
Hutchinson, 1976
Buku Teks
Gujarati, Damodar N., author
McGraw-Hill , 2009
Buku Teks
Kennedy, Peter, author
MA Blackwell Publishing, 2008
Buku Teks
Lahiri, Kajal, author
Wiley India, 2009
Buku Teks
Theil, Henri, author
North-Holland, 1971
Buku Teks