Manoch, D., Kunathikom, S., Thaweechaithaworn, T., Phophong, P. and Laokirkkiat, P. 2004. Hypoosmotic Swelling Test of Sperm Supplemented with Pentoxifylline after Preparation by Two-layer Percoll Gradient Method. Siriraj Medical Journal. 56, 4 (Apr. 2004), 186–190.