Phumdoung, S., B. Manasurakarn, K. Rattanasombat, S. Mahattanan, K. Maneechot, B. Chanudom, and S. Kaewnak. “Effect of the Prince of Songkla University Birthing Bed on Duration, Pain, and Comfort Level During Second-Stage Labor in Primiparous Thais”. Pacific Rim International Journal of Nursing Research, vol. 17, no. 1, Feb. 2013, pp. 56-67, https://he02.tci-thaijo.org/index.php/PRIJNR/article/view/6364.