1. Coal: back to the future: the future of coal from a global perspective;Williams,1993
2. Al-Kamil Coalfield Development, pre-feasibility Economic Evaluation study;United;Project OMA/90/010,1995
3. Nuruddin Abdullah bin Humeid Al-Salmi, Tuhfat al-a'yaan bi-seerat ahl-Oman, Vol. 2, 2nd edn (in Arabic). Al-Istiqamah Bookshop, Muscat, Sultanate of Oman, undated, pp. 310–312.