Norwich sign Fer
Fer and Olsson are two of a number of new arrivals at the club with manager Chris Hughton having been on a summer spending spree.
Fer's fellow Holland international Ricky van Wolfswinkel became the club's record capture at £8.5million while England Under-21 winger Nathan Redmond was last week purchased from Birmingham and defender Javier Garrido has signed permanently after a loan from Lazio.
He became an integral part of the squad, earning widespread praise, before his move in 2011 to FC Twente and after further impressing there he was on the brink of a switch to Everton in January this year.
However, the transfer fell through after a knee problem arose during a medical and the clubs failed to agree on renegotiated terms.
Fer represented Holland at all levels from under-17 before making his bow in the senior team in the August 2010 friendly against Ukraine.
Fer then made his full senior debut against Turkey in a World Cup qualifier.