Bibi and Tina are the main characters of the same named German audio book for little children. It's a side series of Bibi Blocksberg playing on a farm. Tina and the Martinshof appeared in the Bibi Blocksberg episode Der Reiterhof Teil 1 and Der Reiterhof Teil 2 the first time. Later in 1991 the audio book series Bibi und Tina started. There are currently 57 episodes.