T. B. L. Webster, Monuments Illustrating New Comedy, 3rd ed. rev. by J. R. Green and A. Seeberg, London, 1995, 2, p. 382, 4XT10 (item one) and 4XT9 (item two); and J. H. Betts, J. T. Hooker and J. R. Green (eds), Studies in Honour of T. B. L. Webster, 2, Bristol 1988, p. 125, no. 15, pl. 13.17 (item one) and no. 14, pl. 13.16 (item two).
The slave mask is a type borrowed from Old Comedy, cf. M. Bieber, The History of the Greek and Roman Theater, Princeton, 1971, p. 102, fig. 388, for a similar terracotta roundel to item one.