Most of these methods will not have a citable paper. You can cite the SegmentEditor as a tool and refer to its github page and then you can cite the Slicer as a general biomedical analysis platform. These two are the common ones people use:
Fedorov, A., Beichel, R., Kalpathy-Cramer, J., Finet, J., Fillion-Robin, J.-C., Pujol, S., Bauer, C., Jennings, D., Fennessy, F., Sonka, M., Buatti, J., Aylward, S., Miller, J. V., Pieper, S., & Kikinis, R. (2012). 3D Slicer as an image computing platform for the Quantitative Imaging Network. Magnetic Resonance Imaging , 30 (9), 1323–1341. Redirecting
Kikinis, R., Pieper, S. D., & Vosburgh, K. G. (2014). 3D Slicer: A Platform for Subject-Specific Image Analysis, Visualization, and Clinical Support. In Intraoperative Imaging and Image-Guided Therapy (pp. 277–289). Springer, New York, NY. 3D Slicer: A Platform for Subject-Specific Image Analysis, Visualization, and Clinical Support | SpringerLink