I know what I have learned

"I know what I have learned" is a short story by the great storyteller Andrew Lang. The plot of the story describes a man who had three daughters, but all of them were married to trolls and lived underground. In order to visit them he step by step made some actions to see them and come in. Each daughter was a treasure for him and he didn't realize that time what he will have to face with. Have a pleasant reading.