It's a Beitman schematic in the obsolete djvu format. You'll find the djvu plugin and standalone reader at:
http://techpreservation.dyndns.org/schematics/
Here's a free schematic locater from this web site. Not sure why CPU is so high during a search but is handy to have.
http://techpreservation.dyndns.org/USL_FILES/
Richard