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This is to certify that your paper entitled «Estimation of methane emission from the risers of urban gas network in the metropolis of Mashhad and evaluation of its economic and environmental effects» was indexed with 12 pages, in the CIVILICA citation database, code COI:JR_JSAEH-9-3_006, after evaluation and approval of the referees of the "Journal of Spatial Analysis Environmental hazarts Vol 9, Issue 3 , Year 2023.

While offering our congratulations on the indexation of your paper, please be informed that this certificate is prepared based on the information submitted by the secretariat of the above journal and the information contained in the CIVILICA database, and the accuracy of its content can be inquired at any time through link provided at the bottom of the page or scanning the code image.