World's Languages in danger, UNESCO 上索布語音系(英语:Upper Sorbian phonology) 索布語字母(英语:Sorbianalphabet) 下索布語 维基百科提供如下语言版本:上索布语维基百科 Ethnologue上索布語資料(页面存档备份,存于互联网档案馆)
modern West Frisian, London: Oxford University Press, 1913 Stone, Gerald, Sorbian (Upper and Lower), Comrie, Bernard; Corbett, Greville G. (编), The Slavonic
Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press: 66–69, 1999, ISBN 978-0-521-65236-0
Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press: 70–74, 1999, ISBN 978-0-521-65236-0