Organization of the petroleum exporting countries, MacNeill, M., Plakolm, E., Golpashin, D., & Hammer, W. (2013). Organization of the petroleum exporting countries: Annual report 2012. Organization of the petroleum exporting countries.
শিকাগো স্টাইল (17 তম সংস্করণ) উদ্ধৃতিOrganization of the petroleum exporting countries, Maureen MacNeill, Elfi Plakolm, Diana Golpashin, এবং Wolfgang Hammer. Organization of the Petroleum Exporting Countries: Annual Report 2012. Vienna: Organization of the petroleum exporting countries, 2013.
M.L.A (9 ম সংস্করণ) উদ্ধৃতিOrganization of the petroleum exporting countries, et al. Organization of the Petroleum Exporting Countries: Annual Report 2012. Organization of the petroleum exporting countries, 2013.
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