VOICED: Copernicus's remains laid to rest -- again

The video details the rediscovery and identification of Nicolas Copernicus' remains. In 2005, his grave was found at Frombork Cathedral. Scientists identified his remains by matching DNA from a tooth with DNA found in a book he owned. Copernicus was reburied with a marked grave, combining science and luck to solve the mystery.

What role did a book play in the identification of Copernicus?

What combination of elements led to the positive identification of Copernicus's remains?