Gumpel, Henry J.
Commerce Clearing House, 1969
Buku Teks
Kohlhammer, 1961
Buku Teks
Federal Republic, author
Wiesbaden : Wiesbadener Graphische Betriebe GmbH, 1977
Buku Referensi
Heyde, Wolfgang
C.F. Muller Juristischer Verlag, 1999
Buku Teks
Federal Republic of Germany,, 1980
Buku Teks