# Federal Register
1 - 80:23297-23300 - Permit-Required Confined Spaces; Extension of the Office of Management and Budget's (OMB) Approval of Collection of Information (Paperwork) Requirements - PDF
# Regulations
1 - 1910.146(k)(1)(i) - Permit-required confined spaces
# Standard Interpretations
1 - 1910.146(k)(1)(i) - Permit-Required Confined Space Entry Requirements For IDLH and Non-IDLH Spaces