Slate Roofs - National Slate Association - 1926
A Handbook of Data on the Constructing and Laying of All Types of Slate Roofs
The original text of the 1926 slate book that remained the standard authority for decades.
(The National Slate Association also produced a "completely new guide to slate roofing", Slate Roofs - Design and Installation Manual,* in 2010, "84 years after the original 'Slate Roofs'.")