E. ARIF, Ghassan; 						JAAFAR, Sura Y.; 						M. ABDULLAH, , Shymaa.
 Using Least squares methods and nonlinear regression Methods to Calculate the Approximate Value of Ionicity in Terms of the Energy Gap.
<strong>Tikrit Journal of Pure Science</strong>, [S.l.], v. 24, n. 5, p. 97-104, sep. 2019.
ISSN 2415-1726.
Available at: &lt;<a href="http://tjps.tu.edu.iq/index.php/j/article/view/874" target="_new">http://tjps.tu.edu.iq/index.php/j/article/view/874</a>&gt;. Date accessed: 14 aug. 2021.
doi: <a href="http://dx.doi.org/10.25130/j.v24i5.874">http://dx.doi.org/10.25130/j.v24i5.874</a>.