ISBN 978-0-673-16585-5. ↑ ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2011-07-06. Retrieved 2010-03-31. ↑ ↑ Pittsburgh Post Gazette Storytelling: About those knocking Easter eggs March 13, 2009 http://www.post-gazette.com/stories/local/morning-file/storytelling-about-those-knocking-easter-eggs-333664/#ixzz2HRUK2VyB ↑ http://www.wirnowski.com/Carp/Pas_Customs.html ↑ http://www.holidays.net/easter/greekeaster.htm ↑ "The word tsougrisma means "clinking together" or "clashing."