I wrote a couple Niche books just to see how they did. 'The World of Motor Scooters and All my Friends Have Four Legs. These are short books that appeal to a wide audience. They are both ebooks, not available in hard copy yet. I wanted to test the market first.
The World of Motor Scooters is packed with info for any scooter or moped enthusiast to enjoy and All my Friends have Four Legs is for dog lovers.
https://www.amazon.com/s?k=Robert+fetner&i=digital-text&ref=nb_sb_noss_2
