Revision History for USGS 
  Crustal Studies Technical Letter Number 15

  J.H. Healy and G.B. Mangan

  A Progress Report on Seismic Model Studies

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  Posted online at http://pubs.usgs.gov/misc/tl/0015/
  August 8, 2012

  Initial release in paper form
  December 23, 1963

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