How does anyone learn how to authenticate coins ?

I am comfortable grading my own coins but have no clue as how to learn the much more difficult lesson of authentification, are there some classes/good books on this subject??? les
The President claims he didn't lie about taxes for those earning less then $250,000 a year with public mandated health insurance yet his own justice department has said they will use the right of the government to tax when the states appeals go to court.
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From my own experience, authenticating US is not very difficult (it is a lot easier than grading). I've used these materials many times and found them to very helpful, and easy to use, and I have run into coins that were not authentic.
If you have any specific questions about a particular coin, please PM me, or bring it up in the forum for others to comment on.
Brian