That is the case reference number of this watch, 168.(0)010.
http://www.omegawatches.com/planet-omega/heritage/vintage-watches-database?ref=14550
These watches came with both dome and pie-pan type dials.
I wonder if those receipts are for the servicing of the watch, rather than original sale. Since "it's all Greek to me", perhaps our OP can tell us.
With respect to the movement, if it has the "push-pull" date mechanism, it is a cal. 564. If not, it's a cal 561. A 23M serial number would put it right around 1965, which is also the time that Omega was transitioning from the cal. 561 to 564. It could be either.
Very nice pick-up!
gatorcpa
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