Crises and Cycles
It's hard to say what is the most rare, most hard to find, most buried important book, in the history of the Austrian School. But this splendid and critically important treatise would certainly be among the nominees.
Until this edition, this book has been darn-near impossible to obtain short of stealing from the Library of Congress. As a matter of fact, it has been mysteriously missing off the shelves there for years, so the only copies extant have been photocopies of photocopies 50 times over.
So at last: we can present to you Crises and Cycles by one of the greats.
During the thick of the Great Depression, the same year as John Maynard Keynes came out with his treatise, Wilhelm Röpke made this contribution to macroeconomics: an excellent exposition of the Austrian Cycle theory in the tradition of Mises and Hayek.
He refutes Keynes before Keynes became popular, and also provides an argument against other prevailing theories. Röpke is not perfect: while his analysis is excellent, he recommends a reflation after deflation. Nonetheless, this is an important and much-sought-after treatise by an important member of the Austrian School.