Efficient? I'm not sure there's an efficient way. If this is doable with normal hermetic magic, I would go with something like this:
Scribing from the ashes
InIg 20
R: Touch, D: Year, T: Ind, Ritual
This spell is usually cast as a follow up to Tales of the Ashes, for interesting books and scrolls. For this spell to be possible, the caster must have been able to identify ashes belonging to a specific book. If he found a burned down library, with the cinders scattered, the gamemaster may decide that a higher level ritual is needed. As part of this ritual, the caster collects the ashes of the burned book and mixes them with other ingredients to prepare a special ink during the casting of this ritual. For the next year, this ritual allows the caster to see the book while using the specially prepared ink in sufficient details to allow the caster to scribe a copy in an empty book with that ink. The caster may still encounter difficulties with copying the book if the language of the former book is unknown to him, with undecoded labtext shorthand, etc. This might be known beforehand with just Tales from the Ashes if there would have been a book title to gauge the language or content.
(Base 3, +1 Touch, +4 Year)
Now if you're looking at efficiency, use this spell with a group target for a bookcase, or room for a small library which would give you InIg 30.