Expansive Soil Tips
From Advanced Foundation Repair.

Living with Expansive Soils
A guide to foundation maintenance, by Marshall B. Addison, PHD, PE

Soil Behavior
Discussion of expansive soils, from Micro-Flo Industries.

Swelling Clays Map Of The Conterminous U.S.
From SureVoid.

USGS Introduction To Swelling Clays
US Regions and explanations
Index to State Maps