synergic vs synergistic

synergic

adj
  • Of or pertaining to synergy; synergistic 

synergistic

adj
  • Of or pertaining to synergy or synergism; synergic; co-operative, working together, interacting, mutually stimulating. 

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