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This is to certify that your paper entitled «Investigate Spatial and Temporal Changes of Precipitation Hydro-Chemical Parameters (Case study: North Khorasan Province)» was indexed with 10 pages, in the CIVILICA citation database, code COI:SETCONG01_021, after evaluation and approval of the referees of the "The first international conference on research and new achievements in science, engineering and new technologies 2021.

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 conference 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.