[l2h] I can't get it to work on Ubuntu 16.04; I must be doing something really stupid

[wba]

I have a pdflatex job that has worked for years on Windows and Ubuntu.  
I just type "pdflatex c3a.tex" and everything works.  But when I run 
"latex2html c3a.tex" I get, after all the usual noise:

*********** WARNINGS ***********
No implementation found for style `newcent'
No implementation found for style `sd'
No implementation found for style `sd-pf'
No implementation found for style `sd-sf'
No implementation found for style `splitphantom'
No implementation found for style `triplediamond'
No implementation found for style `sd-misc1'
No implementation found for style `graphicx'
No implementation found for style `hyperref'

The file c3a.html is created, but it hasn't processed any of the defined 
commands, and appears to be little more than a copy of the source file.

The four files sd*.sty, along with splitphantom.sty and 
triplediamond.sty are in the local directory.  The other files--newcent, 
graphcix, and hyperref--are, I assume part of the standard latex 
distribution, since they work when I run pdflatex.

The information in http://tug.org/mailman/listinfo/latex2html indicates 
that the latex2html manual can be found at
http://www-texdev.ics.mq.edu.au/l2h/docs/manual/support_tf.html
but that file is listed as "not found" by my browser.

Can anyone help with this?