Geoffrey E (University of the Witwatersrand, South Africa) Blight 
Unsaturated Soil Mechanics in Geotechnical Practice [PDF ebook] 

There are other books on unsaturated soil mechanics, but this book is different. Unsaturated soil mechanics is only one aspect of a continuous range of soil mechanics studies that extends from the rheology of high water content soil slurries to the mechanics of soft soils, to stiff saturated soils, to unsaturated soils, and, at the far end of the r