edited and introduced by Andrew Shonfield and Stella Shaw
Heinemann Educational Books, 1972
Buku Teks
edited by Eleanor Bernert Sheldon and 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
Landis, Paul H.
Ginn and Company, 1961
Buku Teks