- 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
