31485724stiff-leaf book structuresPT2026-03-30 20:56:04UF31485725stiff leaf bindingNDUF31485726stiff leaf binding structureNDUF31485727stiff-leafNDUF31485728stiff-leaf book structureNDUF31485729stiff-leaf structureNDBT31400814books by internal formPTRT31359331board booksPT