APA (7th ed.) Citation

Roberts, R. (2011). Celtx: Open source screenwriting beginner's guide. Packt Publishing, Ltd..

Chicago Style (17th ed.) Citation

Roberts, Ralph. Celtx: Open Source Screenwriting Beginner's Guide. Birmingham: Packt Publishing, Ltd., 2011.

MLA (8th ed.) Citation

Roberts, Ralph. Celtx: Open Source Screenwriting Beginner's Guide. Packt Publishing, Ltd., 2011.

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