Ahmadi, A. ., S. . Gohari, A. . Kondori, and I. Z. . Jaldi. “A Study of Legal Nature of Preliminary Agreements and Its Necessity Fundamentals”. International Journal of Asian Social Science, vol. 3, no. 4, Apr. 2013, pp. 1012-9, https://archive.aessweb.com/index.php/5007/article/view/2472.