Widiastuti, H. “Pengaruh Luas Ungkapan Sukarela Dalam Laporan Tahunan Terhadap Earnings Response Coefficient (ERC)”. Journal of Accounting and Investment, vol. 5, no. 2, Jan. 2016, pp. 187-0, https://journal.umy.ac.id/index.php/ai/article/view/983.