Logbooks yes. I have the logbooks. But logbooks don't contain the
*details* of work done. They should contain references to other
documents. For example a logbook might say that a 100hr check was
done. What it won't say (unless the engineer felt like writing it in
there) is that the landing gear gas seals had to be replaced and two
instrument panel light had to be replaced, etc; that will be in a
separate file which is referenced in the logbook.

This is not correct. 14CFR43 requires that a record be made of the
work done. A 100 hr inspection is just that - an inspection. It is
acceptable to state that a 100 hr inspection was performed and no
discrepancies were found. Any discrepancies found and corrected would
be maintenance in addition to the inspection, and would have to be
recorded. It is acceptable to reference a work order, but a copy of
that work order would have to be attached to the maintenance records.
In practice, this often means the mechanic returns the logbook AND a
copy of the work order to the owner. The owner then promptly loses the
copy of the work order, since to him it's just another receipt. The
careful owner will tape/staple/otherwise make the work order a part of
the permanent maintenance record, and this will not happen. Some
owners are so 'careful' that they never throw ANYTHING away, and the
maintenance records are all in one big bag with every receipt for
everything that was ever done in there. Others throw everything away.
Very few (excepting those who do their own maintenance) are anywhere in
between.

If a reference was made to a work order but the work order was not
given to the owner, regulations have been broken. Good luck proving
it, though. If the work is recent the work order will be on file. I
have yet to encounter a repair station that would not make a copy for
the current owner. Yes, they have a right to charge for this but most
won't. But if it's old, forget it. The record is lost.

Michael