"Journal de la Haye", Aug. 7th, 1839 and "Dagblad van 's Gravenhage" Aug. 5th, 1839. Marianne and her friend (or was M. a sort of chambermaid?) visited Scheveningen, a searesort near Den Haag.
You can find the dates of and the number on the deathcertificates here: https://www.wiewaswie.nl/personen-zoeken/zoeken/q/oldaker
and with the dates and number you can search here: http://zoekakten.nl/prov.php?id=UT
. Sorry it's in Dutch.