Helvetica, also known by its original name Neue Haas Grotesk, is a widely used sans-serif typeface developed in 1957 by Swiss typeface designer Max Miedinger and Eduard Hoffmann.
A 1969 poster by Robert Geisser exemplifying the "Swiss" style of the 1950s and 60s: solid red colour, simple images, and neo-grotesque sans-serif type, all in lowercase. This design appears to use Helvetica or a close imitation.