astrict vs keep back

astrict

verb
  • To bind, constrain, or restrict. 

  • To estop. 

  • To restrict the tenure of. 

keep back

verb
  • To restrict or restrain. 

  • To hold back; to refuse to give or share. 

  • To prevent (a pupil) from advancing in a course. 

  • To stay back; to refrain from approaching. 

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