Rabiu, A. B., R. B. Abdulrahim, O. A. Garuba, O. O. Adekanmbi, S. A. Alabi, L. L. Ojurongbe, and A. S. Lawani. “Occurrence of Similar Periods in Geomagnetic Field Variations and Solar Activity”. ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT, Vol. 15, no. SPi2, June 2019, pp. 223-41, https://www.azojete.com.ng/index.php/azojete/article/view/31.