1st edition/1st printing. This book had a tiny print run of only 3,000 copies, and is extremely scarce in excellent condition. This is my personal favorite "what-if" sci-fi story--it's a real thriller! The HAB theory postulates that the earth "flips" when the ice accumulates too heavily at the poles. Has it happened, and could it happen again? The story borrows some theory from Charles Hapgood's Path Of The Poles. Near fine book--straight, clean, tight, with no handwriting in it but with a tiny, faint spot to upper page edges and an almost unnoticeable small indentation on front panel (like something sat on the book). Near fine dustjacket which has been price clipped and has a very short completely closed edge tear upper front panel; otherwise, it is clean, unfaded, crisp.