Searching for multiple tags within multiple groups

Hi – I am trying to find a way to search for all my notes that have any of several tags, in several specified groups. Ie, I want to simultaneously search my groups called “Primary Sources” and “Secondary Sources”, to find all my notes that are tagged EITHER “1928-1945” or “1945-1949”. (Ie, looking for all my bibilography items that cover the period 1928-1949 – although none are tagged with that date range, and my bibliography items are split between “primary” and “secondary” groups.) I know how to find notes in those two groups that have BOTH those tags, but not EITHER tag.
Help! I know this must be possible.
(And I accidentally posted this query to the DT TO GO forum earlier, so apologies if you are seeing this twice)

The only possibility to search for either of these tags right now is to use an advanced search, see Tools > Search > Advanced. An upcoming release will simplify this though.