The following consists of a basic compilation of online sources available that might be helpful in the study of David Jones's life and work. A project is underway to provide a comprehensive online bibliography of all of Jones's own works (visual art, poetry, essays and letters), secondary critical sources and archival holdings.  
N.B. See the website of the David Jones Research Center (Takoma Park, Maryland, USA) for information about their events and activities, including a yearly Jones seminar, the David Jones Digital Archive, and more: www.davidjonesresearch.org 
Online Resources 
​Digitised Images ​(visual art and archival material)
Tate Gallery (London, U.K.), www.tate.org.uk/art/artists/david-jones-1370
Tate Gallery Archive (London, U.K.), www.tate.org.uk/art/archive/tga-8222/drawings-and-watercolours-by-david-jones-photographs-of-his-work-and-source-material
National Museum of Wales (Cardiff, Wales, U.K.), museum.wales/articles/2013-04-04/David-Jones-1895-1974/
National Library of Wales (Aberystwyth, Wales, U.K.), discover.library.wales/primo_library/libweb/action/search.do?ct=&pag=&indx=1&pageNumberComingFrom=4&frbg=&rfnGrpCounter=1&indx=31&fn=search&dscnt=0&scp.scps=scope%3A(44WHELF_NLW)%2Cprimo_central_multiple_fe&fctV=images&mode=Basic&vid=44WHELF_NLW_VU1&ct=Previous%20Page&rfnGrp=1&srt=rank&tab=tab1&fctN=facet_rtype&dum=true&vl(freeText0)=Jones%20%2C%20%20David%20%2C%201895-1974%20&dstmp=1474312324623
Oxford First World War Poetry Digital Archive, www.oucs.ox.ac.uk/ww1lit/search?query=David+Jones&collection=&Search=Go
Kettle's Yard Museum (Cambridge, U.K.), www.kettlesyard.co.uk/collection-artist/david-jones/
Imperial War Museum (London, U.K.), www.iwm.org.uk/collections/search?f%5B0%5D=makerString%3AJones%2C%20David&query=
British Council (London, U.K.), visualarts.britishcouncil.org/collection/artists/jones-david-1895
Laing Gallery, Tyne & Wear Museums (Newcastle, U.K.), collectionssearchtwmuseums.org.uk/#details=ecatalogue.289431
Goldmark Art (featuring engravings by Jones), www.goldmarkart.com/index.php?option=com_virtuemart&view=category&virtuemart_category_id=224
Cardiff University Special Collections Exhibition, scolarcardiff.wordpress.com/2016/05/09/exhibition-david-jones-1895-1974/
Artnet, 'Auction Results' for David Jones, www.artnet.com/artists/david-jones-2/past-auction-results
'Art & Artists' Blog, Ariel Poems Illustrations (incl. 'The Gum Trees,' by DJ), poulwebb.blogspot.co.uk/2013/03/the-ariel-poems-part-2.html
Oriel Tegfryn (Art Wales), 'David Jones - Limited Edition Prints', www.artwales.com/artists-detail-print-ot-en.php?artistID=27
Films 
1965 Interview with Jones and Saunders Lewis (by Tristram Powell), www.youtube.com/watch?v=psQkOT7eNwE&feature=youtu.be
In Search of David Jones: Artist, Soldier Poet​ (Film by Derek Shiel, 2008), www.dailymotion.com/video/xu9moy_in-search-of-david-jones-artist-soldier-poet_creation
David Jones Between the Wars: The Years of Achievement (Film by Derek Shiel and Adam Alive, 2012), www.dailymotion.com/video/x13fk5l_david-jones-between-the-wars-the-years-of-achievement_creation
David Jones: Innovation and Consolidation (Film by Derek Shiel, 2014): www.dailymotion.com/video/x61qixf
BBC Documentary on In Parenthesis​, narrated by Owen Sheers (2016): www.youtube.com/watch?v=iYooScmNvGs&fbclid=IwAR2cDigG6r5zXPlrKKOviMzPM6BvW2fmVvjxz4oDP6b4xUSIzaXZVp0Xn7U
Online Articles & Commentaries
'A Brief Introduction to David Jones.' Arduity.com, www.arduity.com/poets/jones/
David Jones: Artist and Poet, Flashpointmag. Web Issue 13 (Spring 2010). www.flashpointmag.com/index13.htm
David Jones: Culture & Artifice, A Collection of Essays. Flashpointmag. Web Issue 18 (Summer 2016), www.flashpointmag.com
'David Jones, 1895-1974.' Poetry Foundation. www.poetryfoundation.org/poems-and-poets/poets/detail/david-jones
Green, Andrew. '"Sweet sister death has gone debauched today": Artists and Writers in Mametz Wood.' Gwallter. 13 April, 2014. gwallter.com/art/sweet-sister-death-has-gone-debauched-today-artists-and-writers-in-mametz-wood.html
Hart, D.B. "The Lost Modernist." First Things , March 2018. www.firstthings.com/article/2018/03/the-lost-modernist
Yates, Robert. 'David Jones (1895-1974)'. War Poets Association. 2005. www.warpoets.org/poets/david-jones-1895-1974/
​Important Primary Sources for David Jones
Literature & Mythology:
Frazer, James. The Golden Bough: A Study in Magic and Religion. Third Edition. 12 Vols. London: Macmillan, 1906-15. [entire 12-vol. 3rd edition and Supplement (1937) available to download in PDFs here: wordandsilence.com/2017/01/21/classic-jam-hits/]
      First Edition (1890):
        Vol. 1: archive.org/details/goldenboughstudy01fraz ;
        Vol. 2: archive.org/details/goldenboughstudy02fraz
      Second Edition (1900):
        Vol. 1: archive.org/details/goldenboughstudy01frazuoft;
​        Vol. 2: archive.org/details/goldenboughstud02frazuoft;    
​        Vol. 3: archive.org/details/goldenboughstudy03frazuoft
      Abridged Edition (1922): www.sacred-texts.com/pag/frazer/
Y Gododdin (Aneurin; Welsh and English, tr. John Williams, 1852)**, books.google.co.uk/books?id=5U8AAAAAcAAJ&printsec=frontcover&dq=y+gododdin&hl=en&sa=X&redir_esc=y#v=onepage&q&f=false
The Mabinogion (tr. Lady Charlotte Guest)*, www.sacred-texts.com/neu/celt/mab/
Le Morte D'Arthur, Sir Thomas Malory (Caxton ed.)*, Vol. 1: www.gutenberg.org/files/1251/1251-h/1251-h.htm;
​Vol. 2: www.gutenberg.org/files/1252/1252-h/1252-h.htm
Philosophy, Theology & Politics:
Maritain, Jacques. Art et Scholastique. Paris: Art Catholique, 1920., archive.org/details/artetscolastique00mariuoft
Maritain, Jacques, Art and Scholasticism. Translated by Joseph Evans. Scribner, 1962^,
​ maritain.nd.edu/jmc/etext/art.htm
de la Taille, Maurice. The Mystery of Faith: An Outline. Sheed & Ward, 1930.^^, www.ewtn.com/library/theology/myoffait.htm
               PDF: thecatholicarchive.com/wp-content/uploads/2013/02/159.pdf
Spengler, Oswald. The Decline of the West. Translated by Charles Francis Atkinson. New York: Alfred A. Knopf, 1916., archive.org/stream/Decline-Of-The-West-Oswald-Spengler/Decline_Of_The_West_djvu.txt
Religion/Roman Catholic Mass:
King James (Authorized) Version of the Bible, www.kingjamesbibleonline.org
Latin Vulgate Bible with Douai-Rheims English Translation, vulgate.org
Text of Latin Tridentine (Roman Catholic) Mass, www.extraordinaryform.org/ExtraordinaryFormTextLandscape.pdf
Resources for Gregorian Chant and Catholic Liturgy (CMAA), musicasacra.com/resource-lists/
Film of Latin Tridentine (RC) Mass, www.youtube.com/watch?v=pvY_GG8P9GU
Vexilla Regis (Gregorian chant), www.youtube.com/watch?v=Mm0ce0amh6s
*Jones owned several translations, including this one.
**Jones owned the 1888 Stephens translation.
^n.b. Jones would have been most familiar and most influenced by Fr. John O'Connor's translation, The Philosophy of Art, printed at Ditchling in 1923, although subsequent translations have been a more faithful rendering of Maritain's work, such as Scanlan's 1930 translation, of which Jones also had a copy, or this one from 1955. 
^^n.b. Jones's own copy is The Mystery of Faith and Human Opinion Contrasted and Defined from 1934, so there are a few differences but much of the substance of the text is the same.