Inside Marriage, New York, Grove Press, 1960.
Der schönste Tag, Zurich, Diogenes Verlag, 1960.
Ho Ho Hochzeit, Zurich, Diogenes Verlag, 1971.
This 1960 book has been published in at least 3 different formats and titles. I suspect there may also be further translations. The images from the inner pages are taken from the "Der schonste Tag" edition.
I suspect it wasn't very popular in the US, as there was no follow-up, whereas, the "Der Herzinfarkt" followed a year later in Europe. Ungerer cartoons did however appear in Evergreen around the same time. This was another publication in the "Grove Press" family run by Barney Rossett. I wonder how Barney and Tomi got on? Quite well I would expect.