some titles:
The Complete Guide to Marathon Walking by Dave McGovern
Marathon and Half-Marathon: The Beginner's Guide by Marnie Caron, The Sport Medicine Council of BC, and Jack Taunton
26.2 MILES ONE STEP AT A TIME.(Recreation)(A BEGINNER'S GUIDE TO WALKING A MARATHON) : An article from: The Register-Guard (Eugene, OR) IF you look this up on Amazon, it looks like you can download it