كروم رامز. 2020. “Finding the Necessary Conditions for the Existence of the Dark Soliton Solution to the Vakhnenko-Parkes Equation With Variable Coefficients and With Power Law Nonlinearity”. Tishreen University Journal -Basic Sciences Series 42 (5). https://journal.tishreen.edu.sy/index.php/bassnc/article/view/10178.