The "Advanced Search" Org mode tutorial on Worg provides the following example to find all entries with either "Walter" or "Evensong" in the author field:
BIB_TITLE={Walter\|Evensong}
I would like do the same in a custom agenda command. However the following produces a syntax error:
(setq org-agenda-custom-commands
'(("q" tags "BIB_TITLE={Walter\|Evensong}")))
Can you suggest a correct method? I do not need to use a regular expression per se, the above example was the only one I could find.