
- Author: Robert Bickers
- Language: English

- Author: Robert Bickers
- Language: Chinese
- Year: 2019

- Author: Robert Bickers
- Language: English
- Year: 2017

- Author: Robert Bickers
- Language: English
- Year: 2017

- Author: Robert Bickers R. G. Tiedemann
- Language: English
- Year: 2007