Take a look at these writers on writing:
Ray Bradbury- Zen in the Art of Writing
Neil Gaiman - The View from the Cheap Seats
John Gardner - On Becoming a Novelist and The Art of Fiction
Stephen King- On Writing
Anne Lamott- Word By Word
James Michener- My Lost Mexico
Diana Wynne Jones - Reflections: On the magic of writing
Mary Oliver - Rules for the Dance : a Handbook for Writing and Reading Metrical Verse
Mary Oliver - A Poetry Handbook
Kurt Vonnegut - Like Shaking Hands with God: A Conversation about Writing
Eudora Welty- On Writing
Edith Wharton - The Writing of Fiction
The Paris Review has a wealth of interviews with famous writers about their craft. And many are freely available online.
