Kempson, Ruth and Thwala, Nhlanhla and Marten, Lutz (2006) Siswati Clefts: The Meeting Ground of Context and Contrast.

Kempson, Ruth and Cann, Ronnie and Marten, Lutz and Otsuka, Masayuki and Swinburne, David (2001) On What goes Left and What goes Right.