In 1994 the estate of walker Evans gave the Met in NYC a large collection of his work, as stated in the article posted here:
http://www.nytimes.com/2009/02/06/arts/design/06evan.html?pagewanted=all
Of which included images from a body of work that he created with james agee, titled, Many Are Called, a three-year photographic study of people on the New York city subway. Evans employed a hidden camera shooting passengers traveling around the city. Some considered this “a glimpse into the unguarded moments of Depression-era Americans.”
Book #19 if you haven’t guess it is hidden at the Metropolitan museum of art. Not inside, but out.
Approach the museum from E. 83rd cross 5th ave, to the right of the fountain you’ll see a black curved dump pipe coming out of the ground. Your disguised book is stashed behind it.
Good luck and log it here.
Transmissions From The Wastelands 
im gonna look for this tomorrow. its still there right?
As far as I know. Haven’t got an update.
Found it! Thanks so much for creating this fun treasure hunt! (I even took a photo with my phone but can’t figure out how to upload it until I get to a computer.)