📕 Source : UNICEF© 09-TB-Manual drilling techniques. // 2010 // 2 pages.

   ****[<https://www.ri.org//content/uploads/2019/08/Manual-Drilling-Techniques.pdf>](<https://www.ri.org//content/uploads/2019/08/Manual-Drilling-Techniques.pdf>)

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Source : UNICEF© // Release year — 2010.