The Gesta Danorum (Books I-IX) on Ismar
The Danish History, > Book Eight.
attestation: Ismar was the King of the Sclavs who held Jarmerik captive
"Ismar, the King of the Sclavs"
attestation: Ismar kept Jarmerik and Gunn under guard as political prisoners of value
"in charge of Ismar"
attestation: The Sclavic kingdom held power over Danish captives, indicating a period of Danish weakness
"the King of the Sclavs"
attestation: The entire company at the banquet was overcome with drink and perished in the fire
"obsequies of his brother; all the company were overcome with liquor."