Tashkent: Publishing House of the Academy of Sciences of the Uzbek SSR, 1957. — 527 s. The book is a translation of the work of the outstanding Uzbek encyclopedist Biruni (XI in . ). The author describes the ways of calculating time in different peoples, compares and analyzes numerous eras. The work of Biruni gives a rich factual material that allows the chronologist to get an idea of those systems of chronology that people used in different eras and in different countries. Along with this, the book contains many interesting facts from the field of history, astronomy, etc. d. The book is designed for specialists in Oriental studies, astronomers, historians, philologists and all those interested in the history of science and culture of the peoples of Central Asia.