The Cubs' road uniforms had centered numbers in 1972. Here's why
Topps in 1972, Part 1 – SABR's Baseball Cards Research Committee
MLB Jersey & Cap History
Best Uniforms Not Being Used Anymore (AL East Edition) : r/baseball
MORE
A Look Back at MLB Teams Wearing White Pants on the Road
Colors, caps and logos: 113 years of Cubs uniforms
Uni Watch: Celebrating 100 years at Wrigley Field - ESPN
Ron Santo - Wikipedia
MLB Jersey & Cap History
The Cubs should retire several more jersey numbers - Bleed Cubbie Blue
Colors, caps and logos: 113 years of Cubs uniforms