» ...for this mailing activity comprising six different topics and the same number of postal deliveries, envelopes were used made of semi-transparent glassine, an approach frequently copied by others in the meantime. The design concept permitted parts of the document to be already read through the envelope as a result of large areas, clear shapes and typography, thus already awakening interest. The return quota, which was far higher than usual, as well as the many imitators, show us that the approach is a success. «