Ц.Отгонсүрэн, and Д.Түвшинтөгс. “The Morphological Structure of English Prepositions and Their Capacity to Derive Lexical Words”. Acta Mongolica, vol. 16, no. 426, Nov. 2015, pp. 115-24, https://journal.num.edu.mn/actamongolica/article/view/5684.