In a university thesis your friend may get smartie points for citing the refereed academic journals. Try:
Chute, R. D., and Wiener, E. L.. (1995). Cockpit-cabin comunication: I. A tale of two cultures. International Journal of Aviation Psychology, 5, 257-276.
Chute, R. D., and Wiener, E. L.. (1996). Cockpit-cabin comunication: II. Shall we tell the pilots?. International Journal of Aviation Psychology, 6(3), 211-231.