Revision History for USGS 
  Crustal Studies Technical Letter Number 26

  J.F. Gibbs and J.C. Roller

  Seismic-Refraction Measurements of Crustal Structure 
  Between Nevada Test Site and Ludlow, California

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  Posted online at http://pubs.usgs.gov/misc/tl/0026/
  February 20, 2013

  Initial release in paper form
  December 1, 1964

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