Some of the Census 2001 data are in microsoft access files (having filename extensions .mdb). A microsoft access file can have several tables inside, each of which contains data. There is a software called mdbtools that can be used to read access files.
The command mdb-tables can be used to see the names of tables

Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).