Which French writer's first four novels were published under her husband's pen-name 'Willy'?

Colette (Sidonie-Gabrielle Colette, 28 January 1873 – 3 August 1954) was a French novelist nominated for the Nobel Prize in Literature in 1948. Her best known work, the novella Gigi (1944), was the basis for the film and Lerner and Loewe stage production of the same name. She was also a mime, an actress and a journalist.

In 1893 she married Henry Gauthier-Villars (1859–1931) or 'Willy', his nom-de-plume, a well-known author and publisher. Her first four novels, the four Claudine stories, Claudine à l'école (1900), Claudine à Paris (1901), Claudine en menage (1902), and Claudine s'en va (1903) appeared under his name. They chart the coming of age of their heroine, Claudine, from an unconventional fifteen-year-old in a Burgundian village to the literary salons of turn-of-the-century Paris. (The four are published in English as Claudine at School, Claudine in Paris, Claudine Married, and Claudine and Annie).