Revision History for USGS 
  Crustal Studies Technical Letter Number 14

  J.C. Roller, O.P. Strozier, W.H. Jackson, and J.H. Healy

  Preliminary Report on Seismic-Refraction Studies of 
  Crustal Structure in the Western, Central, and Southern 
  United States

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  Posted online at http://pubs.usgs.gov/misc/tl/0014/
  August 8, 2012

  Initial release in paper form
  December 2, 1963

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