I'm looking for sources that give any indication or description of the shooting technique used in longbow/warbow shooting in high-late medieval Europe; aspects like posture, draw length, draw path, anchor point, arrow length, positioning of the arrow on the bow, etc.. Especially of the mid-15th century or earlier (though I already know that's probably asking too much).

Of course I've already gone through as many depictions on my go-to websites Manuscript Miniatures, Armour in Art and Web Gallery of Art, as well as a general google search for archery in art so I'm fairly confident I have already found a decent part of available visual sources but I'm sure I there are still other less obvious sources so any depictions I might have missed are most certainly welcome.

Fortunately the depictions I've been able to find so far give a fairly decent clue as the technique displayed is somewhat consistent throughout the depictions (by which I mean consistent enough to provide a decent starting point in recreating the techniques).
(For those that use facebook and like to see the selection I've saved let me know and I'll send you the link to my album. I could probably also send them by email though.)

However, we don't exactly have an abundance of written and translated treatises for archery to complement the visual sources so I'm hoping someone here has been able to find more sources that give any kind of clue on the kind of technique used for longbows, especially in the context of warfare.
I know I can't be picky considering the scarcity of available sources but if possible written in, or translated to, English would be great. Dutch or German is also fine. Modern writing would be easiest to understand of course but I've not had as much difficulty as expected understanding high-late medieval music and texts in the aforementioned languages so I'll take anything regardless of writing style. Something like French, Italian, Spanish or Latin would become a google-translate affair to me though.

So far I've only been able to find two sources that come close:
1: The art of archery / l'Art d'archerie, author unknown (Edited by Henri Gallice, Translation by H. Walrond, 1901), dated to circa 1515, though stated to be based on fragments from a 15th century French manuscript. [1]
2: Toxophilus or the Schole of Shooting, Roger Ascham, 1545 [2]

The first one surprised me in the level of detail of the instruction given on the shooting technique (for a manuscript that is). It should be noted however that it's rather vague in it's origin and the translator specifically states: “The following translation is not printed without misgiving as the old provincial French terms used by the writer and the construction of some of the sentences are by no means clear, and the modern equivalents of some of the words are not identified even by French experts”.

The second one is slightly later and more of a dialogue than a precise instruction but nevertheless provides another scarce clue.

And before people ask: Of course we have the finds from the Mary Rose that have provided a tremendously valuable primary source but it dates from roughly a century past the heyday of the longbow as a weapon of war (and my period of interest) and we all know arms and armour and warfare itself can and has changed hugely in a century, so while I certainly acknowledge it's importance I don't want to fixate myself too much on taking it as a be-all-end-all source and would like to complete my understanding of historical techniques with additional sources as much as possible.

I'm very new to archery, so please forgive any obvious sources I've missed. I'm sure a lot of academic research has already been done on this subject, I'm sure there have already been plenty of people that have asked this questions and I'm sure a lot is still unknown but I have to start somewhere in gathering it all in one place for myself. I've already become a member of my local longbow/warbow society, which has given my a good basis to start from, but my interest in longbow/warbow shooting is as much from a viewpoint of historical understanding as it is of practical training so I'd like to have as much historical research in the form of depictions and references in manuscripts/literature/artworks/etc. backing up my practical training as possible.

[1] https://www.archerylibrary.com/books/gallice/
[2] https://www.archerylibrary.com/books/toxophilus/

For English sources, there might be something in Barrett or Smythe.

Smythe is here: http://tei.it.ox.ac.uk/tcp/Texts-HTML/free/A12/A12567.html

Can't help with Barrett.

I would start with:

Gaston Phoebus's Book of the Hunt
Anne Curry's translation of all the sources on Agincourt
Michael Livingston's and Kelly DeVries' edition and translation of all the sources on Crecy

Jim Bradbury The Medieval Archer (1992)
Robert Hardy and Matthew Strickland's The Great Warbow
Kelly DeVries's Infantry Warfare in the Early Fourteenth Century (1992, a great Fundgrube ie. a place you go to copy the footnotes and read the sources cited)
Jonathan Waller and John Waller, "The Personal Carriage of Arrows from Hastings to the Mary Rose." Arms & Armour, Vol. 7 No. 2 (2010) pp. 155-177

Possibly articles by Clifford Rogers

Just to clarify, is it written materials on how bows were used tactically, or technical details of how they were shot you are after?

Thank you for all the quick help gentlemen, much appreciated! Looks like I have plenty of reading to do the coming time.

Anthony: I'm looking to recreate the medieval shooting technique of warbows/longbows so I'm only looking for useful information on the actual way archers shot their bow. I'm not looking for battlefield accounts on the tactical use of archers, their effectiveness on the battlefield, the effects of their arrows on armour, etc..
To give you an example, the author of "The art of archery / l'Art d'archerie" clearly states: "Then, holding the arrow by the middle, he must put it in the bow, and there hold it between two fingers, and you must know that these two fingers are the first and second. And every good archer should, as I have said before, draw his bow with three fingers and to his right breast, as by doing so he can pull a longer arrow. ". This gives a clear clue on how many fingers to use for drawing and some indication of the anchor point.