Nathiang, P. “[Retracted Article] : Development of rice seed dropping machine for paddy field with local farmer participation in Uttaradit province [Area Based Development Research Journal, (2019), 11(3), 218-233] (in Thai)”. Area Based Development Research Journal, vol. 12, no. 2, Apr. 2020, p. 158, https://so01.tci-thaijo.org/index.php/abcjournal/article/view/241200.