APA (7th ed.) Citation

Luther, M., & Stump, J. (2006). An Explanation of Luther's Small Catechism. Project Gutenberg.

Chicago Style (17th ed.) Citation

Luther, Martin, and Joseph Stump. An Explanation of Luther's Small Catechism. Project Gutenberg, 2006.

MLA (9th ed.) Citation

Luther, Martin, and Joseph Stump. An Explanation of Luther's Small Catechism. Project Gutenberg, 2006.

Warning: These citations may not always be 100% accurate.