Ronger E. Miller (1971)

Atlanta Reproductive Health Centre (1995)

Kyriacou dan Sutcliffe (1978)

Kyriacou (1987)

Asmah Bee (2004),

Freudenberger (1974)

Farber, (1984)

Pines (1993),

Maslach & Jackson (1981a,1981b)

Salinas (2001)

(PRB, 2005 World Population Data Sheet).

Ramasamy, 2004

Venkat, 2002

Cullen (2001)

Shahaneem dan Alimah (2001),

Norshila, Norhayati dan Ahmad Soufiean (2006)