I have four operating manuals for Railroads plus shipping which is Media Mail.Email in my profile.
Florida East Coast. Rules of Transportation Department,180 pages with addendums 1926 & 1928,measures 4 x6 inches $20
Terminal Railway Association of St Louis Operating Rules 1953,109 pages,measures 4x6.75. $15
Uniform Code of Operating Rules 1950,132 pages,measures 4.125x6.75. $15