Prior to 1906 Chelsea advertised in magazines such as “Country Life in America” and “The Rudder”. From 1906 to 1917 it seems Chelsea felt every 5 years was sufficient for major catalogs, ie, 1906, 1911, and 1917. Catalogs A of 1906 and E of 1911 were large desk sized catalogs. Catalog F of 1917 was the first of several major catalogs that were pocket sized, including 1919, 1920, 1921, and 1923. Here is one of the very few original copies of Catalog F. NAWCC Chapter 8 has reprinted a high quality copy of this catalog and it is well worth the asking price on eBay.