German Irregular Verbs by Vowel Changes
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2 years ago
A few remarks:
1) For presentation purposes, I think the auxiliary verbs deserve a separate treatment, as their stem vowels differ between present sg. and pl. (or at least this should be mentioned), e.g.:
können - sg. kann, pl. können
2) Typos:
In the present tense form for bieten, the final "t" is missing: bietet
In the present tense form for fangen, the "g" is missing: fängt
The past forms for bleichen are blich, geblichen (without t)

3) The following verbs are missing:
wiegen "weigh" (like fliegen),
sprießen "sprout" (like fließen),
spinnen "spin" (like rinnen),
winden "wind", dringen "penetrate, insist" (like finden)
werben "woo, recruit, advertise" (like bergen)
verzeihen "forgive" (like bleiben) - the simplex zeihen "accuse" exists, but is obsolescent
weichen "give way, subside", verschleißen "wear down" (like beißen)

Separate type /ɛː/ /iː/ /aː/ /oː/
gebären, gebiert, gebar, geboren "bear (a child)"

4) Are you sure about the following forms:
a) The weak forms of bersten - I've never encountered them and Duden doesn't know them as well.
b) The perfect participle of  dürfen is gedurft (all modal auxiliaries are ablauting weak verbs).

5) If you want to consequently give weak alternatives where they exist, include the following:
schaffen, schaffte, geschafft "manage"   
scheinen, scheinte, gescheint "shine" - in the presciptive standard, "seem" is strong and "shine" is weak, but people also fequently use the strong forms for "shine"
bleichen, bleichte, gebleicht "bleach" - the transitive verb is always weak, for the intransitive verb "to pale" the strong forms are obsoleescent, they are alive only in the prefixed verbs erbleichen, verbleichen; ausbleichen nowadays normally uses the weak forms, but the strong participle ausgeblichen is still in use, especially as adjective.