According to a report in Kathpress, the Salzburg-based Silent Night Society was the first to be notified of the find. It's a booklet titled “Four Beautiful New Christmas Songs”, printed in Steyr (a town in Upper Austria) by Joseph Greis.
Greis ran a printing business in the early 19th century and the town's first bookstore from 1827. He died in 1835.
The booklet is not dated but Michael Neureiter, president of the Silent Night Society, believes it was printed not long after 1818 when the melody for Silent Night was composed to lyrics written by a young priest called Joseph Mohr, in the small town of Oberndorf near Salzburg. Franz Gruber, a schoolmaster and organist from a nearby village, was the composer.
The original manuscript has been lost. The first surviving edition of the text and music was published in 1833 in Dresden, as part of a collection of Tyrolean Songs.
The song booklet recently discovered in Vienna includes all six verses which Mohr originally wrote.
The first English translation of the popular carol was published in 1859. Silent Night was declared part of Austria's intangible cultural heritage by UNESCO in 2011.
The Silent Night Society is planning to hold 200 anniversary celebrations for the carol in 2018. The Christmas carol has been recorded hundreds of times by popular singers and has even been performed by some Swedish goats.