An article about when to use Relative vs Absolute timestamps. Some basic stuff, but good to have those at one place.
http://uxmovement.com/content/absolute-vs-relative-timestamps-when-to-use-which/
Research conducted at Google as to the effectiveness of secret questions for password reset etc:
http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43783.pdf