cycle, the Younger Futhark was insufficient, having only 16 characters. The solution devised was to add three special runes to represent the remaining numbers: (arlaug; Golden Number 17), (tvimadur or tvímaður; Golden Number 18), and (belgthor; Golden Number 19). In 1636, Ole Worm documented the Younger Futhark numeral system, including these three characters, in his Runir seu Danica literatura antiquissima (Runes: the oldest Danish literature). A version using the Latin alphabet for weekdays and Arabic numerals for the golden numbers was printed in 1498 as part of the Breviarium Scarense. Primstav A primstav is the ancient Norwegian calendar stick. These were engraved with images instead of runes. The images depicted the different nonmoving religious holidays. The oldest primstav still in existence is from 1457 and is exhibited at Norsk Folkemuseum. Modern use Adherents of the Estonian ethnic religion (Maausk) have published Runic calendars () every year since 1978. Until 1991, the calendar was an illegal samizdat publication under the Soviet government. See also Computus Runicus Germanic calendar List of runestones Nationalencyklopedin Scythe sword Dominical letter References Further reading External links Obsolete calendars Specific calendars Calendar Medieval runes Modern runic writing