(EN) Alaric Hall, Chapter 7 - Narratives and Contexts, in Alarichall's works (PDF), p. 138.
«It is problematic, but seems clearly to portray Vanlandi to have been trodden to death by a trollkund being, a mara. This affords an early and respectably close analogue to the Anglo-Saxon conception of maran riding the sick (§6:3.4). What is really useful here, however, is Snorri’s thirteenth-century prose.»