Some level 65 spells come from the
Glyphed Rune Words which drop off of all the mobs listed on that page. Basically level 65+ named in PoP zones.
Some level 65 spells come from
Taelosian Geomancy Stones which drop off of GoD named.
I would recommend just paying someone to research any missing level 65 spells since I think they are all researchable now with the exception of the Ancient GoD spells. The GRW turn ins can be frustrating because the spell returned is random and it could take a lot of turn ins to get every spell available. Find a researcher, tell them what you need and fork over the dough.