Unicorns

Black Unicorn By Tanith Lee.
Dark Lord of Derkholm by Diana Wynne Jones
Dealing with Dragons series.by Patricia Wrede
Elidor, By Alan Garner, Has A Unicorn
Eragon by Chris Paolini
Gold Unicorn.By Lee
Immortals_ series (Wild Magic, Wolf-Speaker etc.)by Tamora Pierce includes a dragon, as well as other mythical creatures.
Into The Land Of The Unicorns By Bruce Coville.
Red Unicorn By Lee
The Divide by Elizabeth Kay.
The Forgotten Beasts of Eld by Patricia McKillip.
The Harry Potter books include a centaur--and a unicorn in the first book.
The Last Unicorn by Peter S. Beagle
The Road To Balinar By Mary Stanton.
The Shadowed Unicorn From Front Street/Cricket Books By Sheila Kelly Welch
Wish Upon A Unicorn By Vicki Blum.
Xanth series by Piers Anthony--one is called Centaur Aisle.
Year of the Griffon by Diana Wynne Jones