VHPI Books and/or Tutorials

[PlayDough]

I post this about once a year to see what has come available.

Can anybody recommend a VHPI book, paper, tutorial, etc? The
standard
itself lacks the clarity that a book or tutorial could provide.

I have looking to use the VHPI for simulation setup and control.
SystemC is a great option, but since the VHPI is included with our
simulator with the base VHDL license, it seems a much cheaper option
than purchasing SystemC.