A finnish article about the ’74 show in Helsinki:
Zappa had in Helsinki, Finland two concerts on September 22, 1974 (famous Helsinki concerts, YCDTOSA vol. 2). Short concert review (“Voihan Zappa!” is on page 89). Before that on September 17 Zappa made a PR trip to Helsinki, described in the main article together with an interview (pp 24-31). The day before concert on September 21 Frank and Gail Zappa attended a wedding in Helsinki, which is included into the main article too. Their wedding present was a cappella performance of Approximate. A lot of funny pictures!
PS. Another nice article in English describing these events (and more) is Frank Zappa in Finland.