http://www.amazon.com/Author-Literary-Detective-Don-Foster/dp/0805068120/ref=sr_1_1?ie=UTF8&s=books&qid=1223552820&sr=8-1
"This fascinating book describes how an English professor became a detective, sort of. Don Foster still teaches literature at Vassar College, but he's recognized as an expert in attributional theory--the idea that everybody has literary fingerprints, or, as he puts it, "no two individuals write exactly the same way, using the same words in the same combinations, or with the same patterns of spelling and punctuation." Foster is now an expert at identifying anonymous authors."