The Adventures of K9 (sic) was a series of four illustrated paperback storybooks for children written by David Martin and published by Sparrow Books in 1980. The four books feature K-9, the character Martin co-created. Specifically, the stories (according to the Discontinuity Guide website) feature K-9 Mark I and are supposed to take place sometime after the events of The Invasion of Time when the Doctor left K-9 on Gallifrey.[1]
A total of four books were published: