How can I find the correct part for a replacement keyboard for an LG laptop

My daughter's laptop (an LG 13U70P) has an A key that broke off. (The base part that connects it is broken.) I've replaced laptop keyboards before, but it's been a while. Just finding the correct keyboard replacement part to order has been a pain. Either I'm looking in the wrong place, or the information is hard to find, or both. So two questions: Which keyboard will be a compatible replacement part? Is there a relatively easy way to find this information?

Question by David Elm on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.