2015 Nonfiction Reading Challenge

I quite enjoyed this one this past year and while I don't know if I made my goal for this past year,  I am going to attempt it once again.  The Introverted Reader has few guidelines, of which the only guideline is that the book is classified as nonfiction.  The levels for the challenge are:

Dilettante--Read 1-5 non-fiction books

Explorer--Read 6-10 

Seeker--Read 11-15

Master--Read 16-20

I am going to go for the Explorer level.  Here are the links to the books I have read for the challenge:
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If you wish to get involved with the challenge, you can sign up at The Introverted Reader.