From a Page of Spell Knowledge you can cast both arcane and divine spells. Crafting it requires Craft Wondrous Item feat, which is pretty useful for crafting other cool things. Turned out like both can be lost, but the Page is also slotless.
A Ring of Spell Knowledge costs 1.5 times more gold, only works with spells from 1st to 4th level, and takes a slot. It also has no use for the Oracle: can't hold a divine spell, and there is a special entry against those spells being used by Oracles:
[List of rings] All of them are useful only to spontaneous arcane spellcasters.
What is the reason to use a Ring of Spell Knowledge at all?