How many books did billy Collins write?

As of 2022, Billy Collins has published eleven (11) books of poetry, including:

- The Apple That Astonished Paris

- Aimless Love: New and Selected Poems

- The Art of Drowning

- Ballroom

- The Trouble with Poetry: And Other Poems

- Nine Horses: Poems

- Picnic, Lightning

- Sailing Alone Around the Room: New and Selected Poems

- Questions About Angels: Poems

- The Trouble with Poetry

- The Rain in Portugal: Poems