Once Upon a Shabbos is one of the few children’s books that feature Yiddish words. Yiddish is a mixture of German and Hebrew, which has been spoken by Jews since the Middle Ages. For more information about organizations dedicated to preserving Yiddish, try some of these links.

• Living Traditions
  http://www.livingtraditions.org/index.htm
• National Yiddish Book Center
  http://www.yiddishbookcenter.org/
• The Workman’s Circle -- Arbeter Ring
  http://www.circle.org/
• YIVO Institute
  http://www.yivoinstitute.org