Foster, J. E., "A Number System Without a Zero Symbol", Mathematics Magazine, Vol.21, No.1 pp. 39-41, 1947.
•
This was the system used to reckon the year based on the four-year Olympiads, so for instance 480 BCE (the date of the Battle of Thermopylae) would be written ἔτει αʹ Ὀλυμπιάδος οδʹ, that is, the 1st year of the 74th Olympiad.