In her thesis, Stephansen generalised Guldberg's work and succeeded in describing all those fourth order partial differential equations which could be reduced to equations of the third order.
Sa kanyang sanaysay, Stephansen generalised Guldberg ng trabaho at Tagumpay na naglalarawan sa lahat ng mga ika-apat na order ng bahagyang kaugalian equation na kung saan ay maaaring bawasan sa equation ng mga third order.