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In the May 26, 2003 edition of Coin World, the hobby newspaper had announced they had contracted investigators to conduct a year-long, comparative study of PCGS, ACCGS, NGC (Numismatic Guaranty Corporation) and several other grading services, each known as a Third Party Grader (TPG).
It is used by nearly all major coin grading companies, the main two being NGC and PCGS.
The influence of the book has caused the incorrect spelling "piefort" to be used by third-party grading services such as NGC and PCGS in labeling coin attributions.