Author not established. UNESCO Institute for Statistics. Date not established. EHREA archive: /library/documents/doc-933c04eae1159c26c51bae82/
[1] UNESCO Institute for Statistics. Original source: http://www.ehrea.org/UNESCO%20Institute%20for%20Statistics.htm. Preserved original: /library/originals/87a3f0203df9f6f8e668d4b9b2586fbf701d5dced8a9fcd55a6ab7875712afb9.html. SHA-256: 87a3f0203df9f6f8e668d4b9b2586fbf701d5dced8a9fcd55a6ab7875712afb9