1. Bartholdi, J. J., & Hackman, S. T. (2019). Warehouse & Distribution Science. Georgia Institute of Technology. Chapter 4, Section 4.1, "Storage media," describes various rack types, noting that cantilever racks are used for storing items like lumber and pipe. (Available via Georgia Tech SCL website).
2. Material Handling Institute (MHI). (n.d.). Racks. MHI Industry Groups - Rack Manufacturers Institute (RMI). The RMI section on the MHI website describes cantilever racks as being "ideal for storing long, bulky, or irregularly-shaped loads such as furniture, lumber, and pipe."
3. Tompkins, J. A., White, J. A., Bozer, Y. A., & Tanchoco, J. M. A. (2010). Facilities Planning (4th ed.). John Wiley & Sons. Chapter 10, "Material Handling," Section 10.5.2, "Storage Equipment," details that cantilever racks are designed specifically for storing long loads such as bars, tubes, and lumber.