I've become a big fan of his and just finished "More Readings from Richard Proenneke: Journals from 1974-1980"  This came out a few years ago and is excellent.
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And I recently ordered "The Early Years: The journals of Richard Proenneke 1967-1973".  This came out in 2011 I believe and both are over 450 pages with some nice pics also. I think this is the only place you can get this one right now. Steep price but quality paper and pics.
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I've read the book "One Mans Wilderness twice and own a couple of the DVD's too.  I was disappointed to learn that that book was paraphrased by Sam Keith the editor and RLP wasn't all that happy that they changed his wording.

These 2 recent releases are edited down but verbatim and come with clarifications on who the people and places are that he refers to. These are very helpful. I highly recommend both of these.  Supposedly there will be a final release of his journals from 1981- till the end around 2000 or so.

Here is a recent tribute to Dick that has some great footage I never saw before.
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Ummm, my guess is because this man's wilderness is full of wonderful folks looking for a way in. Or is it out? I forget.