* [[history:DirectorsOldObs|List of directors]]
  * [[history:Kaiser]]
  * [[history:Bakhuyzen|The brothers van Sande Bakhuyzen]]
  * [[history:DeSitter|De Sitter]]
  * [[history:Hertzsprung]]
  * [[history:Oort]]
  * [[history:Hulst|Van de Hulst]]
  * [[history:afterhulst|After van de Hulst]]
  * [[history:indie|Dutch East Indies]]