Butzer, Karl W & Helgren, David M books & textbook
LIVESTOCK, LAND COVER, AND ENVIRONMENTAL HISTORY: THE TABLELANDS OF NEW SOUTH WALES, AUSTRALIA, 1820-1920
Butzer, Karl W & Helgren, David M
Annals Assoc Amer Geog /2005T Pamphlet
LATE CENOZOIC EVOLUTION OF THE CAPE COAST BETWEEN KNYSNA AND CAPE ST. FRANICS, SOUTH AFRICA
Butzer, Karl W. & Helgren, David M.
Quaternary Research /1972T Pamphlet
