Gaskell, David R., author
McGraw-Hill, 1981
Buku Teks
Gaskell, David R., author
Scripta, 1973
Buku Teks
Gaskell, David R.
Taylor and Francis, 2008
Multimedia
Gaskell, David R., author
Taylor & Francis Group, 2008
Buku Teks
Upadhyaya, G.S., author
Pergamon Press, 1977
Buku Teks