I see a three seat "triplet" nine foot-long bike. Looks to be 1950's/1960's. The tag on the back of each seat reads "Valk" (likely Dutch). Has anyone ever heard of "Valk" as a manufacturer of bicycles from this or any era, either single, tandem or longer? My interest is to know that this triplet is manufactured and authentic rather than homemade. There is so little information out there on vintage 3,4,5, and 6-seat longbikes. Thank You.