After SHTF, you will be facing all kinds of problems , needing all kind of info to take care of. You may need a few bits of info in first aid, measurement conversion, construction math, electical DIY, or laws of physics.

Where would you get those QUICKLY ???

One good source is the Pocket Reference Book

( I don't have it, but seen a number of preppers mention it online. )

Another source of QUICK reference are the Academic quickstudy barcharts
They are 8.5x11 laminated guides in all sorts of fields of knowledge. From first aid to nursing, anatomy, to accounting.

The laminated guides have three holes for 3-ring binders.

I have absolutely no affiliation to these sources of info. I only seen these laminated guides yesterday in a local bookstore, and thought to share with other preppers