Fondell E, Lagerros YT, Sundberg CJ, Lekander M, Balter O, Rothman KJ, Balter K. Physical activity, stress, and self-reported upper respiratory tract infection. Med Sci Sports Exerc. 2011 Feb 1;43(2):272-9.
Knox D, Gibson L, Zusman ME, Gallmeier C. Why college students end relationships. Coll Stud J. 1997 Jan 1;31(4):449-52.