run the examples with pdflatex or latex

All examples with an ps in the file extension
must be run with latex->dvips->ps2pdf

The file extension .???crop has no further meaning,
it was only needed for the book production.
Commands like \AtBeginDocument, \setlength, aso are
often also without a special meaning and only valid
for the book production.

If you find in an example two \documentclasses commands,
then simply delete one.