Brilliant, positively brilliant. Thanks so much Christine. Mystery solved.
For the record, as Christine's link points out, this was the X (tenth) World-wide Congress of Otorrinolaringologia and it was held in Venice, Italy between May 21 and 25 in 1973. In addition to all the medical sessions noted within the link, it's nice to know the good doctors had varied "social programming, with excursions for the islands of Venice, serenatas in the gondolas, parties of beginning and closing in the Ducal Palace."
And it's extra nice to know attendees got a paperweight to commemorate the event.