Earlier in his career, Kolkman worked as a Unix System Administrator at NetHold from February 1996 until April 1997, and as a Scientific Administrative Assistant at ASTRON from April 1992 until July 1993.<ref>[http://www.nlnetlabs.nl/~olaf/ Olaf's personal page]</ref> | Earlier in his career, Kolkman worked as a Unix System Administrator at NetHold from February 1996 until April 1997, and as a Scientific Administrative Assistant at ASTRON from April 1992 until July 1993.<ref>[http://www.nlnetlabs.nl/~olaf/ Olaf's personal page]</ref> |