Where to find the Utopian Calendar
The Utopian Calendar is referenced in the Wikipedia article for the Darian Calendar.
It’s also referenced numerous times in Tom Gangale’s description of the Darian Calendar.
The Mars Asset Registry uses an earlier version of the Calendar, with a stretched clock and no short weeks.
The Mars Calendar app by Laurie Harrison features the Kepler Calendar.
More Mars time links
Papers by Tom Gangale
If you want more detail on the various design choices in the Darian Calendar, this is where to look. No-one has given this subject more attention than Tom Gangale and Marilyn Dudley-Rowley.