Who wrote the novel Rowan of rin?

Emily Rodda did. she also wrote the

Rondo series which are The Key to Rondo, The Wizard of Rondo and The Battle for Rondo)

and the Deltora Quest series (which im not going to name because there are too many)

i have read most of the Rowan of Rin books and all of the Rondo and Deltora Quest books.