Organisation for Economic Co-operation and Development, 1986
Buku Teks
edited and introduced by Andrew Shonfield and Stella Shaw
Heinemann Educational Books, 1972
Buku Teks
edited by Eleanor Bernert Sheldon; Wilbert E. Moore
Russel Sage Foundation, 1968
Buku Teks
Kenneth C. Land
Springer Science, 2012
eBooks
Pierce, Eleanor B.
Pan American Airways, 1965
Buku Teks SO