typology - sign languages

[MARIA GALEA]

Hi there,
Does anyone know of any ongoing research on the classification/ typology
of sign languages.
the only information I have so far managed to obtain is from the
Ethnologue website http://www.ethnologue.com/language/asf

an additional problem I have is that on the webpages of Ethnologue that
talk of BSL, AUSLAN and New Zealand SL - they refer to Johnston 2003 - but
this is not listed in their bibliography list. Does anyone know which
exact work (by Trevor Johnston) this may refer to?

Many thanks!
Maria Galea