Alphabetize references according to the last name of the author.
Andrews, A. A. ...
Butler, B. B. ...
Cohen, C. C. ...
If there is more than one author, then alphabetize by the first name listed.
Andrews, A. A., & Cohen, C. C. ...
Butler, B. B. ...
Cohen, C. C., & Andrews, A. A. ...
If there is no author, then alphabetize the reference by the first word in the title.
O'Tool, O. O. ...
Oxford English Dictionary ...
Peters, P. P. ...
If there is more than one reference by the same author, arrange them in chronological order.
Smith, S. S. (2000). ...
Smith, S. S. (2010). ...
If more than one reference by an author has been published in the same year, assign a different letter to each one and use it in both the in-text citations and the references:
In-text citations:
... (Jones, 2012a).
... (Jones, 2012b).
References:
Jones, J. J. (2012a). ...
Jones, J. J. (2012b). ...