Chennai has two CSIR research institutions namely Central Leather Research Institute and Structural Engineering Research Centre. Chennai Book Fair, an annual book fair organised in Chennai by the Booksellers and Publishers Association of South India (BAPASI), is the largest exhibition for Tamil book publishers to display their books. The fair is typically held for about 10 days between the last week of December and the third week of January.[415] The forty-first edition of the fair was held in 2018.