Their answers range from practical survival guides to books that inspire post-apocalyptic utopias. Pick up a copy and stick these in your doomsday bunker - or on your bookshelf for rainy day reading.

Tech billionaires are building luxury doomsday bunkers, according to a tell-all book by Douglas Rushkoff. Sources: The Guardian, "Survival of the Richest: Escape Fantasies of the Tech Billionaires ...