http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
interlaboratory precision of the penetration test for paving bitumens when the test is done at 15c̊ with a 200g load and a 60s loading time
"Project 109: Durability tests for bitumens."
Includes bibliographical references (page 18).