Burroughs, Edgar Rice

You can get a copy from Abe Books, check out this link.
http://www.abebooks.com/servlet/SearchResults?an=Edgar+Rice+Burroughs&fromanz=fromanz&sortby=96&sts=t&tn=Tarzan+and+the+Madman&x=49&y=11

It's still under copyright, as it says in the wikipedia article. You might find it in one of the popular ebook stores.

Who has this book: Tarzan and the Madman?
http://en.wikipedia.org/wiki/Tarzan_and_the_Madman