Petyim, S., Choavaratana, R., Kunathikom, S., Laokirkkiat, P. and Prechapanich, J. 2007. Freezing Effect on Post-Thawed Sperm Characteristics Especially Sperm DNA Integrity Comparing between Liquid Nitrogen Vapour and Computerized Program Freezer. Siriraj Medical Journal. 59, 6 (Nov. 2007), 298–302.