Abstract
This article also appeared in Indagationes mathematicae.
| Original language | English |
|---|---|
| Pages (from-to) | 565-570 |
| Journal | Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen: Series A: Mathematical Sciences |
| Volume | 59 |
| Issue number | 5 |
| Publication status | Published - 1956 |