The main reference for this period of seals is the 4 volume corpus by Zacos/Veglery 'Byzantine Lead Seals'. You might want to check some libraries, as this
work is quite impossible to buy. Then there's Cheynet and Morrison 'Sceaux Byzantins de la
collection Henri Seyrig', which is easier to purchase, and Laurent's 'La
Collection C. Orghidan', which is also heavy on
monograms.
Zacos II, like
vol. I also beautifully published, is currently available through M&M in
Germany is the main reference for the later centuries.
Of course the DO books are also readily available for purchase, but they are useless for these monogrammatic seals as these books only list seals bearing place names (except
Vol VI with imperial and patriarchal seals), not just individuals. Next to these there are a couple of minor references.
But finding a reference for a non-imperial seal is relatively hard - there thousands of them that basically are all very
rare... many are
still unpublished.
Regards
Gert