For the Kathāvatthu of the Abhidhamma Piṭaka, the PTS edition lists the source of each quotes at page 401-404 (slide 453-456 of the PDF version):
Interestingly, they also list the quotes that they did not manage to find the source:

So possibly some suttas not preserved in the Pali Canon!
Although, that compilation was done in 1915, without the useful search function we have now at our fingertips so some of these quotes might have a source in the Pali suttas that they would have missed at the time…
Here are the untraced quotes:
PTS p.74 (sl. 126)
“Here the religious life is practised?”
PTS p.119 (l.1-3) (sl.171)
“They who ‘mong souls beset by doubts, past all doubt
Have won, and now unswayed, from bonds enfranchised
Abide, to them a great reward is given”
PTS p.169 (sl.221)
“Under the Exalted One Kassapa, Ānanda, I lived the higher life for supreme enlightenment in the future”
PTS p. 197 (sl.249)
“Yea! Verily this mind and mental states
Are void of soul for one who understands.
Whose discerns the low and high in both,
The seer, he knows that neither can endure”
PTS p.225-226 (sl.277-278) – approximately Ang. v.292
“There are, bhikkhus, three modes of volitional acts of body, four modes of volitional acts of speech, and three modes of volitional acts of mind, all of which amount to immoral deeds, bringing forth ill and entailing it as result. And there are a like number of modes of volitional acts of body, speech, and mind amounting to moral [karma], bringing forth and entailing happiness as result.”
PTS p.318
“As doth the holy flame its offering,
As doth the bounteous earth the summer rain,
So doth the Order, in rapt thought expert,
The Gift accept”
PTS p.321
“Neither in this world nor in any other is any to be found better than, equal to the Buddha who has reached the summit of them who are worthy of offerings, who are desirous of merit, who seek abundant fruit”
PTS p.325 (sl. 377) – see Dialogues, ii. 114 f, & 112 ; i.55.
“By the higher knowledge, bhikkhus, do I teach the Norm, not without the higher knowledge; a Norm with [reference to] cause do I teach, not one without; a wonder-working Norm do I teach, and none not wonder-working. And that I, bhikkhus, thus teach the Norm, a homily should be made, instruction should be given, to wit, let this, bhikkhus, suffice for your content, let this suffice for your satisfaction and for your gladness: - the Exalted One is Buddha Supreme! The Norm is well revealed! The Order is well trained! Now when this declaration was uttered, ten thousand world-systems trembled.”
PTS p.346 (sl. 398)
“Not Vessabhu nor yet the Petas’ King,
Soma, Yama, or King Vessaraṇa –
The deeds that were his own do punish him
Who ending here attains to other worlds”
PTS p.348 (sl. 400)
“For him who was hitherto been quite pure in karma of deed and of word and of livelihood, this Ariyan Eightfold Path will go to perfection of development”