2017 https://books.google.com/books?hl=en&lr=&id=jmcPEAAAQBAJ&oi=fnd&pg=PA174&dq=%22global+catastrophic+risk%22%7C%22catastrophic+risk%22%7C%22x+risk%22&ots=J10K9lT-WH&sig=OzmB-Fz87aYWqWUHEL-Gx6TqQoI Book chapter Medium