Erasmus University Library Rotterdam
Burgemeester Oudlaan 50, 3062 PA Rotterdam
P.O. box 1738, 3000 DR Rotterdam, the Netherlands
To gain access to letters that cannot be viewed online or downloaded due to copyright restrictions, you can send an access request to library @ eur-nl.libanswers.com
For more information on Jan Tinbergen and his collections at Erasmus University Rotterdam, visit https://www.eur.nl/en/library/collections/jan-tinbergen-collection.