Random context tree grammars and tree transducers. - Frank Drewes; Christine du Toit; Sigrid Ewert; Johanna Högberg; Brink van der Merwe; Andries P. J. van der Walt (South Afr. Comput. J., 2005)

Bag Context Tree Grammars. - Frank Drewes; Christine du Toit; Sigrid Ewert; Brink van der Merwe; Andries P. J. van der Walt (Fundam. Informaticae, 2008)