Ref. Michael J. Hogan, A Cross of Iron:

Does "Ref." here mean "Reference"?

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The National Security State or Doctrine, generally referrs to the ideology and institutions (CIA, Dept. of Defense) established by the National Security Act of 1947[1], an enduring legacy of then President Harry S. Truman, in support of his doctrine [2] "to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures." (Ref. Michael J. Hogan, A Cross of Iron: Harry S. Truman and the Origins of the National Security State, 1945-1954. New York: Cambridge University Press, 1998; which "explains the transformative process that ended in the ultimate demise of the New Deal state with its emphasis on social spending and ushered in the militarist National Security State.") [3]

Source: Source Watch
https://www.sourcewatch.org/index.php/National_Security_State