The paper refers to the paper of Meijer et al from 1991: https://maartenfokkinga.github.io/utwente/mmf91m.pdf https://maartenfokkinga.github.io/utwente/mmf91m.p

The paper refers to the paper of Meijer et al from 1991: https://maartenfokkinga.github.io/utwente/mmf91m.pdf https://maartenfokkinga.github.io/utwente/mmf91m.pdf Paramorphisms' section is at page 5. It refers to the 1990 paper by Lambert Meertens that your reference attributes to 1992.