¹⁸Lavelle, Des. Skellig: Island Outpost of Europe. Montreal: McGill-Queen's UP, 1976. 12-14.
Among other sources, the Viking practice of  "tossing of infants on top of their lances to and from each other" is mentioned in The Vikings: A History by Robert Ferguson (2009). (Skaar, Freydis. " Ranvaik Owns This Box: The Vikings: A History." Open Letters Monthly an Arts and Literature Reviews. Web. 28 Aug. 2013. <http://www.openlettersmonthly.com/ranvaik-owns-this-box/>.)
Of course, it may be that this account of the Norsemen's brutality is hyperbole. There is always this possibility.