Here are images of the four stamps in a set commemorating the inaururation of the Yaoundé to Ngaoundéré railway line, designed by French artist Claude Durrens (1921-2003), and issued by Cameroun on June 10, 1974, Scott Nos. 589-591.
Map of Cameroun showing railway route, engraved by Claude Durrens.
Laying rails, engraved by Claude Haley.
Welding joints in track, engraved by Claude Jumelet.
Djerem River Bridge, engraved by Jacky Larrivière.