If you'd like to cite the myPersonality project, please use:
Kosinski, M., Matz, S., Gosling, S., Popov, V. & Stillwell, D. (2015) Facebook as a Social Science Research Tool: Opportunities, Challenges, Ethical Considerations and Practical Guidelines. American Psychologist.
If you'd like to cite a specific questionnaire, please use the following references (feel free to expand this list!):
Five Factor Model of Personality: Goldberg LR, et al. (2006) The international personality item pool and the future of public-domain personality measures. J Res Pers 40(1):84–96.
Satisfaction with life scale: Diener E, Emmons RA, Larsen RJ, Griffin S (1985) The satisfaction with life scale. J Pers Assess 49(1):71–75.