I picked out a selection of the finest examples, mostly those that advertise a serial that was beginning in the given issue, some are promoting a short story like "Common Sense Cutler." Nearly all of these are Fleming Stone detective novels that were later published by either George H. Doran (until about 1922) and then Lippincott, her book publisher for most of her career. The final one pictured (Skeleton at the Feast) is a Kenneth Carlisle mystery and he was the detective character who was published by Doubleday Doran's "Crime Club."
Scroll away, gang!
One of Well's serials that appeared in a "slick" magazine rather than a pulp. Her work also regularly appeared in the dream publication of her era -- The Saturday Evening Post. Usually it was her poetry and humor they bought. OH! The title of the book the boy is reading is How to Develop a Pleasing Personality. Took me a while to discern that!