Ridley, John R. Channing, John. text Oxford [England] Boston Butterworth-Heinemann 1999 monographic x, 293 p. : ill. ; Industrial safety 660.2804 WOR 0750645601 http://www.loc.gov/catdir/toc/els033/99035497.html http://www.loc.gov/catdir/description/els033/99035497.html http://www.loc.gov/catdir/toc/els033/99035497.html http://www.loc.gov/catdir/description/els033/99035497.html