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Heike Kamerlingh Onnes was the doctoral advisor of Pieter Zeeman, who is known for his work on the Zeeman effect, the splitting of spectral lines in the presence of a magnetic field. Onnes was a Dutch physicist who was awarded the Nobel Prize in Physics in 1913 for his investigations into the properties of matter at low temperatures, which led, among other things, to the liquefaction of helium.