一般注記"The schemes were prepared by Mr. Clarence W. Perley ... [formerly] chief of the Classification division."--Prefatory note.
Originally included in skeleton form only in the synopsis printed at the beginning of the P-PA scheme published in 1928. Complete in 1933 and made available in type-written form to the staff of the Library of Congress and to classifiers in other libraries by inter-library loan. cf. Prefatory note.