Olivera et al (1992) AO1
Birch et al (1990) AO1
:) Brown & Ogden (1994) AO2
:) Lowe et al (1998) AO2
:( However... AO2
Westcombe & Wardle (1997) AO1
Liou (2001) AO1
:) Rapoport (2003) AO2
:( However/Steptoe et al (1995) AO2
