ICA, OKEH UM, Oyeka.
Simultaneous Estimation of Adjusted Rate of Two Factors using Method of Direct Standardization.
Global Journal of Science Frontier Research, [S.l.], sep. 2015.
ISSN 2249-4626.
Available at: <https://journalofscience.org/index.php/GJSFR/article/view/1648>. Date accessed: 25 may 2022.