While the layout, date code information, and index are very well done, many marks are dated incorrectly.... some off by decades. This is very misleading and frustrating. Due to the Kovels' apparent vast experience, collectors and dealers tend to believe whatever they write... right or wrong! As an author and china mark historian, I hope the Kovels remove any unverified mark usage dates in a future edition. To list a few examples, they say mark 195L is semiporcelain, 1886-1898. The correct information according to the manufacturer (now Syracuse China, then Onondaga Pottery) is vitrified china 1897-1946. Also they indicate mark 127J is a current mark, but this backstamp was actually used 1930s - early 1950s. Then there is mark 105N listed as faience 1891+, which should be porcelain 1959-1969 according to the company. Other knowledgeable and observant collectors and dealers have noticed similar discrepancies.