00285nam a22001217a 4500020001800000082001300018100001800031245003600049260002900085300001000114650001300124650002600137 a9788121923842 a668.9BHA aBhatnagar,M.S aA textbook of polymers Vol 111 aNew DelhibS.Chandc2004 a552 p apolymers acondensation polymers