OSHA Standard 29 CFR 1910.25 - Portable Wood Ladders
OSHA Standard 29 CFR 1910.26 - Portable Metal Ladders
OSHA Standard 29 CFR 1910.27 - Fixed Ladders
OSHA Standard 29 CFR 1917.118 - Fixed Ladders
OSHA Standard 29 CFR 1926.1053 - Ladders
Portable Ladder Safety - Missouri University2
Purchase and Proper Use of Ladders
Stairways and Ladders - OSHA's Technical Page
Walking and Working Surfaces-OSHA's Technical Page