Page xii, preface, paragraph 1 indicates that the 1st Edition in 1957 "...was patterned after the Felt/Spicer formula except that the real-estate rating was dropped, leaving such considerations to be included as part of the location rating."

This text does not make it clear that Location was not actually included until almost 20 years later in the 1975 4th Edition (aka Revision III), as indicated on page 1 of that edition's text.