Piyada Chittanon. (1999) The effect of cryopreservation on structure and viability of spermatozoa of Rana tigerina. Mahidol University,:ม.ป.ท.Piyada Chittanon. 1999. The effect of cryopreservation on structure and viability of spermatozoa of Rana tigerina. ม.ป.ท.:Mahidol University,;Piyada Chittanon. The effect of cryopreservation on structure and viability of spermatozoa of Rana tigerina. ม.ป.ท.:Mahidol University, 1999. Print.