instruction: Give a list of all the names of people that Arboe trained under?
context: Arboe was born at Rønne on the island of Bornholm, Denmark. He was the son of Otto Henrik Arboe and Oliva Elisabeth Saxtorph. He attended the Royal Danish Academy of Fine Arts building school and ornament school from 1855 to 1862 where he was a student of Gustav Friedrich Hetsch (1788–1864) and also trained under Niels Sigfred Nebelong (1806–1871).
response: Gustav Friedrich Hetsch and Niels Sigfred Nebelong