Lan Hayden. International Film Guide 2012. International Film Guide. 2012: 66. ISBN 978-1908215017. Rose, Steve. Extinct review – doughnut-shaped critters
retirement mappings(页面存档备份,存于互联网档案馆) Linguist List - List of Ancient and Extinct Languages explanation by Håvard Hjulstad ISO 639-3 status from the ISO