royal stremma vs stremma

royal stremma

noun
  • Synonym of stremma (“a decare”) 

stremma

noun
  • A Greek unit of land area, now equal to a decare (1,000 m²) but (historical) previously 10,000 square Greek feet. 

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