What is the best book(s) you would recommend for Professional Military Education (i.e. on/off Professional Military Reading Lists)?

<p>Many leaders recommend developing a 'professional library' throughout your career.&nbsp;What are those time-honored classics as well as new titles that redefine the subject of (fill in the blank).&nbsp;I'm sure this will&nbsp;be a fun and informative&nbsp;topic that'll spark some discussion on the subject, as well as promote professional reading/development and well rounded "professional library."&nbsp;Of course, today when we speak of "books" we may also include: audio books; videos/ documentaries; mp3s, or any other format or delivery method, the important thing here&nbsp;is content/substance. Here's just a few ideas on subject matter: military/government; business; leadership; success &amp; achievement; human behavior/psychology; philosophy; management; finances; training/systems/ technical,&nbsp;or anything else applicable, and the titles, well... we'll leave those up to you. Hopefully, this helps spur some&nbsp;thought on&nbsp;professional reading and development, and&nbsp;will&nbsp;prove helpful;&nbsp;now let's get this thing started, thank you for all that you do, and... see you all in the discussion threads!&nbsp;</p>