The family is known through their connections to the Luitingh-Sijthoff publishing company and to several regional newspapers like the now defunct Haagsche Courant.
Sijthoff has since resigned as Commissioner of Het Financieele Dagblad and sold his company interests.
Willem Sijthoff, a grandnephew of Bob,[3] together with a company known as HAL Investments, became the new owners of Het Financieele Dagblad.
[7] On 11 March 2009, The Hague court convicted Sijthoff to 18 months in prison for extortion.
[9] In an article in Quote in July 2006, Jort Kelder states that a confidant of Willem Endstra told him that Sijthoff bought two pit houses in Amsterdam from Endstra in March 2001, through the mediation of Willem Holleeder.
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