Houghton Monogram 689 (nmo:Monogram)
- URI
- http://numismatics.org/sco/symbol/monogram.houghton.689
- Monogram 689 from Houghton, Lorber, and Hoover, Seleucid coins : a comprehensive catalogue (2008). The monogram contains Δ, Τ, Σ, and Ο as identified by Peter van Alfen. (en)
- Δ, Τ, Σ, and Ο
- http://nomisma.org/id/greek_numismatics
- http://nomisma.org/id/seleucid_coins
