Rizaj earned his BA in History from Skopje University in 1956 and his doctorate from Sarajevo University in 1965. He is one of the founders of the Department of History of the University of Pristina, where he taught from 1965 until he retired in 1987. He also worked as a Special Consultant for Turkish State Archives in Istanbul from 1989 to 1990. Rizaj is still active in writing and in 2010 was awarded as "Educator Emeritus" by the Kosovan government.
Fields of interest
He has done extensive research in Turkish Archives in Istanbul, and the British Library in London. During his studies, he mastered Serbian language, Ottoman Turkish, as well as modern Turkish language and English. He has written extensively on Albanian history, with an emphasis on Kosovo. His research gave him enough scientific material to produce several books, most prominent his 1982 book "Kosovo during the 15th, 16th, and 17th centuries" in which he emphasizes that Kosovo was dominated by ethnic Albanians during and after the Middle Ages, a claim refuted by modern historiography.
He also wrote a university textbook " History of the New Era (1453-1789)", published in 1985.
Rizaj's most notable publications include:
- Mining in Kosovo and surrounding regions from the 15th to 17th Centuries (Doctoral Dissertation), Pristina, 1968
- The Albanian League of Prizren in English Documents, 1878-1881, Pristina, 1978
- Kosovo during the 15th, 16th, and 17th Centuries, Rilindja Publishing, Pristina, 1982
- History of New Era 1453-1789, University of Pristina Textbook, 1985
- The Albanians and the Serbs in Kosovo, Zeri i Rinise Publishing, Pristina, 1991
- Kosova and Albanians, Yesterday, Today and Tomorrow, Pristina, 1992
- Kosova, Albanians and Turks, Yesterday, Today and Tomorrow, Yayinevi Publishing, Istanbul, Turkey, 1993
- English Documents on the Albanian League of Prizren and the start of the Disintegration of the Balkans, 1877-1885, Pristina, 1996
- The Albanian's Historical Right to Self-Determination, Pristina, 2005
- The Falsifications of Serbian Historiography, Pristina, 2006