Revision History for USGS 
  Crustal Studies Technical Letter Number 17

  W.H. Jackson and J.H. Healy

  Preliminary Report on Some Factors Affecting Shotpoint 
  Efficiency

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  Posted online at http://pubs.usgs.gov/misc/tl/0017/
  August 8, 2012

  Initial release in paper form
  February 10, 1964

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