Comrie, Bernard. 2005. "Writing systems." Martin Haspelmath, Matthew Dryer, David Gile, Bernard Comrie, eds. The world atlas of language structures, 568-570
Dmitri Egorov, Matthias Urban, Robert Mailhammer, Matthew S. Dryer, Evgenia Korovina, David Beck, Helen Geyer, Pattie Epps, Anthony Grant, and Pilar Valenzuela
Ian. 2008. Glottalized Consonants. In: Haspelmath, Martin & Dryer, Matthew S. & Gil, David & Comrie, Bernard (eds.) The World Atlas of Language Structures