"Fredrik Engelstad" (in Norwegian). Dept. of Sociology and Human Geography, University of Oslo. 20 February 2009. Archived from the original on June 7, 2009. Retrieved 1 March 2009.
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"Fredrik Engelstad" (in Norwegian). Dept. of Sociology and Human Geography, University of Oslo. 20 February 2009. Archived from the original on June 7, 2009. Retrieved 1 March 2009.