Other variations include

- Dual authors

• ( surname and surname , date )
• E.g.  ( Chan and Peter , 2007 )

-More than two authors

• (surname et al ., date )
• E.g . (Chan et al . ,2007 )

-Work by different authors generally

• (surename , date ; surname , date ) in alphabetical order 
• E.g . (Lee , 2005 ; Sue , 2006 ; William , 1999 )

-Different publications by the same author

• (Surename , date , date ) in ascending order 
• E.g ( Lewis , 1991 , 1998 ).