assiduously vs obdurately

assiduously

adv
  • In an assiduous manner; diligently, industriously. 

obdurately

adv
  • In an obdurate manner; stubbornly, intractably or inflexibly. 

How often have the words assiduously and obdurately occurred in a corpus of books? (source: Google Ngram Viewer )