Pointer to some fairly standard mechanical problem?

Let me preface that I'm NOT a mechanical engineer - I'm just trying to
do a back-of-the-envelope design of a little gadget. The internal part
is pretty straightforward, but the whole thing needs to sit in a case
that can be submerged in water to a couple tens of meter.
Now I'm assuming that there's such a thing like a "collection of
formulas for standard geometries" (or such) where I could look up how
thick I need to make the walls of an oblong cylinder made of material
X if it is supposed to survive indefinitely external overpressures of
Y psi. What I don't know is where I'd start looking for this kind of
thing.
So if someone could give me the name of an author I should look for in
the library or the pointer to a web-page that has this kind of thing,
I'd be grateful.
Thanx