Gitti & Erica

 

The sisters Gitti and Erica became very popular around the year 1977, when they sang the title song of the famous Heidi Anime on German television. At this time they used a photo for autographs showing both wearing blue jeans vests. 

pictures found at ebay

I think, it were this kind of denim vests, they were wearing on the photo, brand elkont: