Gunnlaugr composed a Latin biography of King Óláfr Tryggvason. This work is now lost but it is believed to have been an expansion of the Latin Óláfs saga Tryggvasonar written by his monastic brother, Oddr Snorrason. Snorri Sturluson made use of Gunnlaugr's work when composing his Heimskringla and sections of Gunnlaugr's work were incorporated into Óláfs saga Tryggvasonar en mesta.
Gunnlaugr also wrote a Latin biography of Bishop Jón Ögmundarson. This work is also lost but Old Norse biographies of Jón are still extant. Gunnlaugr also composed the original Latin version of Þorvalds þáttr víðförla but it is only preserved in an Old Norse translation. Gunnlaugr was also involved in the collection of Þorlákr helgi's miracles. Gunnlaugr is known to have written on Saint Ambrose and recent research indicates that the extant Old Norse translation of Vita sancti Ambrosii, Ambrósíus saga, may be Gunnlaugr's work.
Gunnlaugr wrote the poem Merlínússpá, a Norse translation of Prophetiae Merlini by Geoffrey of Monmouth. The imagery in Gunnlaugr's translation testifies to his extensive knowledge of skaldic poetry. The poem is preserved in Hauksbók and consists of a total of 171 fornyrðislag stanzas.
- Sometimes Anglicized Gunnlaug Leifsson.
- Þingeyrarklaustur (Historical Places in Northwest Iceland)
- Simpson 2004:166.
- Katrín Axelsdóttir 2005:349.
- Eysteinn Björnsson (2002). Index of Old Norse/Icelandic Skaldic Poetry. Published online at: http://www.hi.is/~eybjorn/ugm/skindex/skindex.html See in particular "Gunnlaugr Leifsson" at http://www.hi.is/~eybjorn/ugm/skindex/gleifs.html from the editions of Finnur Jónsson and E. A. Kock.
- Guðrún Nordal (2001). Tools of Literacy : The Role of Skaldic Verse in Icelandic Textual Culture of the Twelfth and Thirteenth Centuries. University of Toronto Press. ISBN 0-8020-4789-0 pp. 168–169.
- Katrín Axelsdóttir (2005). "Gunnlaugur Leifsson og Ambrósíus saga" in Skírnir, Autumn 2005:337-349. ISSN 0256-8446
- Oddr Snorrason (translated by Theodore M. Andersson) (2003). The Saga of Olaf Tryggvason. Cornell University Press. ISBN 0-8014-4149-8
- Simpson, Jacqueline (2004). "Olaf Tryggvason versus the Powers of Darkness" in The Witch Figure: Folklore Essays by a Group of Scholars in England, pp. 165–187. Routledge. ISBN 0-415-33074-2