APA
National Federation of Roofing Contractors, . (1991). Profiled sheet metal roofing and cladding: a guide to good practice. London: NFRC.
Chicago
National Federation of Roofing Contractors, . 1991. Profiled sheet metal roofing and cladding: a guide to good practice. London: NFRC.
Harvard
National Federation of Roofing Contractors, . (1991). Profiled sheet metal roofing and cladding: a guide to good practice. London: NFRC.
MLA
National Federation of Roofing Contractors, . Profiled sheet metal roofing and cladding: a guide to good practice. London: NFRC. 1991.