Introductory articles
McFall on the composition of the psalm book
https://lmf12.files.wordpress.com/2012/11/psalms.pdf
Smith-Domeris on the History of Explanation
http://otgateway.com/articles/SmithDomeris_HistoryOfPsalmsStudies.pdf
Augustine
http://www.newadvent.org/fathers/1102055.htm
The Utrecht psalter
http://psalter.library.uu.nl
Psalm 1-106
Ps. 4 - The Septuagint
http://www.katapi.org.uk/katapiNSBunix/Lxx/LxxByBC.php?GB=19&GC=4
Ps. 5 - Smith
http://www.satsonline.org/sats_drupal6/userfiles/Smith,Psalm5.pdf
Ps. 8 - NASA posts another impressive photo of the universe every day on its website
http://apod.nasa.gov/apod/ap050908.html and http://antwrp.gsfc.nasa.gov/apod/astropix.html
M.F. Maury (sea currents)
http://en.wikipedia.org/wiki/Matthew_Fontaine_Maury
Ps. 15 - The Septuagint
http://www.katapi.org.uk/katapiNSBunix/Lxx/LxxByBC.php?GB=19&GC=13
Ps. 22:1
http://www.bijbelaantekeningen.nl/files/dict?H07837
Ps. 27:1 - (Mountain) fortresses in the Negev from the King's time:
http://www.bible.ca/archeology/bible-archeology-exodus-kadesh-barnea-iron-age-fortresses-central-negev-rudolph-cohen-1979ad.htm
The mountain fortress of Ein Hatzeva, see here and here.
Ps.27 in Judaism (Yamim Noraim 'the awesome days')
https://schechter.edu/why-do-we-recite-psalm-27-from-rosh-hodesh-elul-until-hoshanah-rabbah/
http://www.betemunah.org/awesome.html
http://www.tedmontgomery.com/bblovrvw/C_5a.html
Ps. 31:6 - According to Johann Bugenhagen, Luther in his dying hour quoted this verse
http://beck.library.emory.edu/luther/luther_site/luther_c_verso.html
http://beck.library.emory.edu/luther/luther_site/luther_c_recto.html
An English translation of the entire sermon
http://beck.library.emory.edu/luther/luther_site/luther_text.html)
Ps. 33:2 - for contemporary reconstructions of the musical instruments, see
http://www.templeinstitute.org/gallery.htm and http://www.moshefrumin.com
Ps. 42:7 - Hermon
http://www.bibleplaces.com/mthermon.htm
Banias/Ceasarea Filippi
http://www.bibleplaces.com/mthermon.htm
Ps. 45:2 - Scripture in Israel
http://en.wikipedia.org/wiki/Zayit_Stone
Ps. 56:9 - Jars of tears in Egypt
http://www.symbolforschung.ch/files/pdf/Hornung_Mischwesen.pdf
In ancient times
http://www.lachrymatory.com/antiquity.htm
http://www.tearbottle.com/Tear_Bottles_Past.html
Ps. 72:4 - Social attitude according to ancient text discovery in Qeiyafa
http://www.eurekalert.org/pub_releases/2010-01/uoh-mah010710.php
http://qeiyafa.huji.ac.il/ostracon2.asp
Ps. 83 - Does it relate to the current situation in the Middle East
http://www.bijbelaantekeningen.nl/blog/2012/11/21/psalm-83-in-oorlogstijden/
Ps.90 - Lioy
http://www.sats.edu.za/userfiles/Lioy,%20Psalm%2090.pdf
Ps. 91 - Spurgeon
Psalm 91 by C. H. Spurgeon (blueletterbible.org)
Elliot
Jim Elliot - Wikipedia
Ps. 94 - Septuagint
http://www.katapi.org.uk/katapiNSBunix/Lxx/LxxByBC.php?GB=19&GC=93
Ps. 104:5 - No flat earth
http://www.refdag.nl/artikel/1404297/Kerk+geloofde+niet+in+platte+aarde.html
Ps. 104:6 - Barker
http://faculty.gordon.edu/hu/bi/Ted_Hildebrandt/OTeSources/19-Psalms/Text/Articles/Barker-Ps104-GTJ.htm
Ps. 106 - Journey through the desert
http://www.ancientexodus.com/
Excursions
Excursion 1 "Literary Aspects.
Logotechnical analysis of Labuschagne: http://www.labuschagne.nl/psalms.htm
V.d. Lugt: http://books.google.nl/books?q=lugt+cantos+and+strophes&btnG=Boeken+zoeken
Excursion 5 'Disease and healing'
Medicine in ancient times: http://www.biblicalarchaeology.org/daily/ancient-cultures/daily-life-and-practice/medicine-in-the-ancient-world/