When was Het Wonderlijke leven van Willem Parel created?

The question "When was Het Wonderlijke leven van Willem Parel created?" is a bit tricky. There's no single answer, because it depends on what you mean by "created."

* The book itself was published in 1973. This is the date when it became publicly available.

* The story was first written in 1963. The author, Pieter van Gestel, started writing the story in 1963, but it took him 10 years to finish it.

So, depending on what you mean by "created," the answer is either 1973 or 1963.