The book? Whose book? Virginia Woolf's? And then Michael Cunningham also used this name to name ...?

The book? Whose book? Virginia Woolf's? And then Michael Cunningham also used this name to name his novel?

Context:

From Mrs. Dalloway to The Hours:
Rethinking the Relations Between Women and Feminism

Introduction
Virginia Woolf's virgin novel Mrs. Dalloway was published in 1925. It is set against the early 1920's London. The original name of the book was The Hours. Michael Cunningham based his novel The Hours on Virginia Woolf and Mrs. Dalloway; it was published in 1998 and awarded the Pulitzer Prize the following year.