I have many combination wrenches but this is the only one I have with a spanner on one side. It has no numbers or makers mark.  I would guess this would be a bicycle wrench. Is there a book telling use for these multi-wrenches?

I would say it's a bicycle wrench. The large open end with the protruding tang would be for adjusting/tightening bottom bracket locknuts with the cranks still on.

That's what they were sold as when I bought mine, which I think I still have around somewhere.  Specifically made for "English" three speeds with the Sturmey-Archer geared hubs, although they worked on other bikes, too.  The thin metal let you reach into spots unreachable with a conventional wrench, and they're surprisingly strong, accepting a certain amount of light tapping with a hammer when the nut you need to remove is really happy where it is and doesn't want to move.

As for a book, never saw one; you just learned which opening fit which nut/bolt on your bike.