- Author: Paul Leo Butzer Rolf J. Nessel
- Language: English
- Year: 1971
- Author: Paul L. Butzer Rolf J. Nessel (auth.)
- Language: English
- Year: 1971
- Author: Paul Leo Butzer Rolf J. Nessel
- Language: English
- Year: 1971
- Author: Butzer P.L. Nessel R.J.
- Language: English
- Year: 1971
- Author: Paul Leo Butzer Rolf J. Nessel
- Language: English
- Year: 1971
- Author: Paul Leo Butzer Rolf J. Nessel
- Language: English
- Year: 1971