We use AMA guide

Journal article (1-6 authors):
1. Hu P, Reuben DB. Effects of managed care on the length of time that elderly patients spend with physicians during ambulatory visits. Med Care. 2002;40(7):606-613.

Journal article with more than six authors:
2. Geller AC, Venna S, Prout M, et al. Should the skin cancer examination be taught in medical school? Arch Dermatol. 2002;138(9):1201-1203.

Journal article with no named author or group name:
3. Centers for Disease Control and Prevention (CDC). Licensure of a meningococcal conjugate vaccine (Menveo) and guidance for use--Advisory Committee on Immunization Practices (ACIP), 2010. MMWR Morb Mortal Wkly Rep. 2010;59(9):273.

Electronic Journal article:
If you have a doi (preferred):
4. Gage BF, Fihn SD, White RH. Management and dosing of warfarin therapy. The American Journal of Medicine. 2000;109(6):481-488. doi:10.1016/S0002-9343(00)00545-3.