Hayk Mirzayans Insect Museum offers training courses, and helps other scientific research centers in completion and maintenance of their insect collections. ITRD acts as the National Identification Service for governmental or non-governmental organizations, publishes various articles, reports, books, data banks and checklists of its holdings, and provides these information free of charge to all visitors. Hayk Mirzayans Insect Museum The Hayk Mirzayans Insect Museum (HMIM) is the largest insect collection in Iran with over 4 million insect specimens, including 20–25,000 local species, hundreds of primary types and paratypes, and a representative collection of exotic insects, especially tropical butterflies. In 1943, Iranian entomologist established a
Holdrian comma Holdrian comma In music theory and musical tuning the Holdrian comma, also called Holder's comma, and sometimes the Arabian comma, is a small musical interval of approximately 22.6415 cents, equal to one step of 53 equal temperament, or formula_1 (). The name comma is misleading, since this interval is an irrational number and does not describe the compromise between intervals of any tuning system; it assumes this name because it is an approximation of the syntonic comma (21.51 cents)(), which was widely used as a measurement of tuning in William Holder's time. The origin of Holder's comma resides in the