The International City Manager's Association, 1947
Buku Teks
MacCorkle, Stuart A.
D.C. Heath and Company, 1948
Buku Teks
Rabinowitz, Alan, author
John Wiley & Sons, 1969
Buku Teks
Bool, J., author
Uitgevers-Maatschappij, 1930
Buku Teks
Burger, B., author
N. Samsom, 1965
Buku Teks