The 21-year-old Swedish midfielder has confirmed that he had phoned Fulham boss Roy Hodgson personally to notify him of his decision to join the Dutch side from Kalmar.
"It was a difficult decision to make because I have been so well received by all the clubs I visited.
"It felt almost a bit sad to have to call Roy Hodgson and say no to Fulham but I felt that I needed to call him myself.
"To take the jump into the Premier League is a very big step. But, I'm only 21 now and can play in a major league in the future.
"My goal is of course to play at the highest level possible."