LONDON — Doctoral students the world over have long despaired about the grueling hours required to obtain a Ph.D. Just ask Colette Bourlier, age 90.

This week, Ms. Bourlier became one of the oldest people in France to be awarded a doctorate, 30 years after she first began researching immigrant workers in Besançon, in eastern France.

She wrote all 400 pages of her thesis by hand, according to her thesis adviser, Serge Ormaux, vice president of the Université de Franche-Comté in Besançon, where she received the degree.

On Tuesday, she was awarded a doctorate in geography after being questioned for more than two hours by an academic jury.