I’m not sure why an Author post-type has a “title” taxonomy, unless you meant books or something, or even why you can’t use the built-in published date field, but here goes:
Store the date published as a timestamp in a custom field. You can do the conversions behind the scenes and just show users the actual dates. And then filter by meta value when retrieving the posts. You can learn more about how exactly to do this over at the codex: http://codex.wordpress.org/Class_Reference/WP_Query#Custom_Field_Parameters