He wrote a wide range of material: poems (both for children and adults), mystery novels (four of them under the pseudonym Bernhard Borge), essays, and articles.

In this novel he introduced the psycho analyst Kai Bugge who claims that a psychologist is more able to solve a real crime than a police officer.

After a particularly hideous murder, Bugge and police officer Hammer, join forces to solve the impossible mystery.

Where Hammer looks for material clues and interviews the suspects about things like motive and alibis, Bugge makes an analytical approach.

This novel is also featured by Kai Bugge in opposition to literary critic, Gabriel Mørk and policeman, Harald Gran.

The deceased had left a diary in which he revealed his growing obsession by the pond, which ends with a confession that he has no choice but to commit suicide by drowning himself.

Kai Bugge re-enters the scene, but even if he solves the strange mystery and sheds light on the hidden pattern, he plays no central role.

Enhjørningen consists of three novellas and a short story bound together by the challenge between psychology and the unicorn — representing the supernatural forces in existence.

Bjerke also published the short story collection, Hobby-detektiven where the very unusual police officer, Klaus Vangli is the hero.

His hobbies covers chess, astronomy, optics, philately, track and field, football betting and other interests that has seems to have nothing in common.