A friend of mine is chasing after two socalled redbooks.
I believe they are now unclassified but **** hard to find.
publications were published by
NDRC Division 6 · Sub-Surface Warfare
Summary Technical Reports of the National Defense Research Committee
the books we look for are
Volume 11 Calibration Measurements
Volume 12 The Design and Construction of Crystal Transducers
Any leads very much appreciated !