Documenting a bug -- WHEN was package XYZ installed

[Richard Owlett <rowlett@access.net>]

I am trying to track what I suspect is a documentation bug. There are 
circular references. To logically break the chain I need to know the 
date package XYZ was installed.

I thought this would be an "apt" related question. But its manpage gave 
no indication that "when installed" is recorded.

Is there at least a way to track what required XYZ to be installed?

TIA