Below is an interesting entry about entrepreneur André-Gustave Citroën, his family and his French companies.
André's father, Levie Citroen, originated from Amsterdam; the Dutch surname Citroen being pronounced 'Seetroon'
When the Citroen family moved from Amsterdam to Paris in 1873, the diaeresis (two dots) was added to the family name to assist with French pronunciation.
André Citroën was born in Paris five years after his family settled there.
Robert
https://www.newworldencyclopedia.org/en ... ve_Citroen