Zone System Calibration Manual by Joseph Saltzer.

AMPHOTO, 1979. First edition, softcover with spiral plastic binding, fine except top and bottom plastic spirals on binding are broken.  64 pages.  Illustrated with zone system graphs and charts designed to provide guidance on exposure, expansion and compression of negative densities, and related topics.  Helpful as an adjunct to the author’s A Zone System for All Formats. In the first edition, Zone System Calibration Manual is a scarce book in any condition.