APA (7th ed.) Citation

Jack, B. (2020). Internal and external validity. Georgetown University.

Chicago Style (17th ed.) Citation

Jack, Billy. Internal and External Validity. [Washington, D.C.]: Georgetown University, 2020.

MLA (9th ed.) Citation

Jack, Billy. Internal and External Validity. Georgetown University, 2020.

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