APA (7th ed.) Citation

. https://doi.org/10.3138/ptc-2019-0104

Chicago Style (17th ed.) Citation

. https://doi.org/10.3138/ptc-2019-0104.

MLA (8th ed.) Citation

. https://doi.org/10.3138/ptc-2019-0104.

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