<ref name ="Østreng 2013">{{cite book |last1=Østreng |first1=Willy |last2=Eger |first2=Karl Magnus|last3= Fløistad|first3=Brit |last4= Jørgensen-Dahl|first4= Arnfinn|last5=Lothe |first5=Lars |last6=Mejlænder-Larsen |first6=Morten |last7=Wergeland |first7= Tor |date= 2013|title=Shipping in Arctic Waters: A Comparison of the Northeast, Northwest and Trans Polar Passages |publisher= Springer |location= |isbn=978-3642167898 |doi=10.1007/978-3-642-16790-4 }}</ref>}}