
- Author: Duane P. Schultz/Sydney Ellen Schultz
- Language: English
- Year: 2016

- Author: Duane P. Schultz
- Language: Portuguese
- Year: 2019

- Author: Duane P. Schultz
- Language: Portuguese
- Year: 2015

- Author: Duane P. Schultz
- Language: Spanish
- Year: 2011

- Author: Duane P. Schultz Sydney Ellen Schultz
- Language: English
- Year: 2008

- Author: Duane P. Schultz Sydney Ellen Schultz
- Language: Spanish
- Year: 2008

- Author: Duane P. Schultz Sydney Ellen Schultz
- Language: English
- Year: 2017

- Author: Duane P. Schultz, Sydney Ellen Schultz
- Language: Spanish
- Year: 2010

- Author: Duane P Schultz, Sydney Ellen Schultz
- Language: English

- Author: Duane P. Schultz Sydney Ellen Schultz
- Language: English
- Year: 2012