references on digitizers

[dac at hoqaa.att.com]

This is only indirectly a GRASS question, but I figured you all were
probably the best folks to ask this.  I need to get up to speed on
digitizers and scanners, so I am looking for references.  General kinds
of material - on the technology, and what`s in use these days.  Any help
would be much appreciated - maybe respond directly by email so as not
to clog this mail with non-GRASS info.

Thanks!

Dave Copperman
dac at hoqaa.att.com