Smith, Joan Macfarlance
Routledge & K. Paul, 1972
Buku Teks
University of London Institute of Education, 1979
Buku Teks
Frey, James H., author
Sage Publications, 1983
Buku Referensi
Fern, Edward F., author
Sage, 2001
Buku Teks
Magnusson, Eva, author
Cambridge University Press, 2015
Buku Teks