(1) Nashwan Shoukry Abdullah ,urban system in Duhok Governorate , Dar speriz, Duhok , 2009.
) 2) Gamal Hamdan , geography of cities, i2, world of books press, Cairo, 1972.
3) Mohamed Azouz, urban housing problems, urban underdeveloped areas of Skikda city as a model, unpublished master's thesis, Faculty of Humanities and Social Sciences , University of Mentouri Constantine , Algeria , 2006.
4) Dina Dajani, Mohammed Yasar Abdin, (trends of urban concentration in the Syrian Arab Republic ), Journal of Damascus University of Engineering Sciences , vol.25, No. 2 , 2009.
(6) Moayad Sami Abdullah Abbas , urban polarization and its impact on the urban environment of Kirkuk, master's thesis , Faculty of Education , Tikrit University , 2016.
(7) Ahmed Mohamed Abdel Aal , (quantitative measures introduced to some geographical phenomena), Journal of Arts and humanities , Sinai University , volume 29, 1998,.
(8) rushood bin Mohammed Al-khorayef , urbanization and the growth of cities in Saudi Arabia, Kuwait, 2007, p. 35
10) Thaer ayasra, (geographical features of the urban system in Jordan ) , Journal of Humanities and Social Sciences , University of Jordan , Vol.41, No. 2, 2014.
(11) Khalaf Hussein Ali Al-Dulaimi , Planning Community Services and infrastructure (foundations-standards technologies), Dar Safa , Amman , 2009.
(12) Zain al-Abidin Ali Safar , geography of cities , first edition , Al-Wahdah publishing house , Amman , 2015.
(13) Abdul Razzaq Abbas Hussein , geography of cities , Al-Ani press , Baghdad , 1977 .
14) Salah Hamid al-Janabi, commercial function of Basra city, master's thesis (unpublished ), Faculty of Arts , University of Baghdad , 1974.
16) Mohamed Abdel Baqi Ibrahim, the role of investment in urban development , scientific symposium No. 1 of the work programs of Cairo governorate and the future vision , 2001.