I have been working on a commentary on the Psalms. I have decided to compile some helpful links that I discovered during my research. It includes a mix of exegetical and sermonic links. Here is what I have for Psalm 42 (in no particular order). Feel free to mention any that you find helpful in the comments section.
The Fathers on Psalm 42: https://pursuingveritas.com/2019/08/27/the-fathers-on-psalm-42
Literary analysis of Psalm 42: http://psalmsstudy.com/psalms-literary-analysis-by-chapter/literary-analysis-psalm-42-presence-god
Into the Word with Paul Carter: https://ca.thegospelcoalition.org/into-the-word/psalms-42-43
Analysis by C. J. Labuschagne: https://www.labuschagne.nl/ps042-43.pdf
William Barrick’s notes: https://drbarrick.org/files/studynotes/Psalms/Ps_042.pdf
John Piper, Spiritual Depression in the Psalms: https://www.desiringgod.org/messages/spiritual-depression-in-the-psalms