 | 02-11-2021 Sergej Yushkevitch: |
| (Analyse)opmerking toevoegen Account aanvragen | ||||
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| There is no "NN" as the co-author. There is indicated in HD-December 1989 on the page 79 under the diagram 158: "J.H.v.Leeuwen + Red.". J.v.d.Boogard was the Redator of problematiek in that time, so, authors of this problem are J.H.v.Leeuwen and J.v.d.Boogaard | |||||