Goodreads asked Edward R. Etzkorn:

Where did you get the idea for your most recent book?

Edward R. Etzkorn When I was growing up, my family owned a stretch of farmland adjoining New York's Catskill Mountains. Its weathered farmhouse fronted a year-round stream, and over a hill in the rear, a spring arose in a swamp where pollywogs, frogs, and salamanders thrived. With Howe Caverns not far away, I always dreamed of my own cavern opening up nearby. Gunther's Cavern began as a series of stories I told my younger brothers and sisters, in which a boy and his sister--yes, Gunther and June--found just such a cavern

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