Year 28 BC was either a common year starting on Saturday , Sunday or Monday or a leap year starting on Saturday or Sunday ( link will display the full calendar ) of the Julian calendar ( the sources differ , see leap year error for further information ) and a common year starting on Saturday of the Proleptic Julian calendar .
Year 28 BC was either a common year starting on Saturday , Sunday or Monday or a leap year starting on Saturday or Sunday of the Julian calendar .