If you still haven't read John Green's brilliant tear-jerker of a love story, now is the time! Although it is one of the most successful young adult novels of all time, this book has a massive and devoted adult following. Another reason you should read it now? The film adaptation comes out June 6.
Warning: although this is a solid choice for outdoor reading, it will make you cry. Oh boy will it make you cry. You may not want to experience an inevitable fit of heaving sobs in public, but it'll be worth it.