Monark cycles also known as Cykeifabriken monark AB, established in Varberg, Sweden, by Birger Svensson in 1908.
In 1961, Monark merged with Nymanbolagen, Uppsala, Sweden, into Monark crescentbolagen or MCB. Monark is also a brand of Brazilian bicycles related to the original Swedish monark AB. (from wikipedia)
The Pettersson Brothers rode these bikes to three consecutive TTT world titles 1967-1969. Two of them (Erik & Sture) on the orange Crescents, while Gosta & Thomas rode the light blue Monarks.
Gosta won the 1971 Giro d'Italia on a Monark, although that was a custom made bike (said to be) a De Rosa painted blue.
REF: Classic Rendezvous