shilling sign vs sou

shilling sign

noun
  • The symbol '/' used in the United Kingdom before decimalisation to separate shillings from pence when writing out sums of money. (Examples: 7/6 = seven shillings and six pence; 7/- = seven shillings exactly.) 

sou

noun
  • An old French copper coin equal to one twentieth of a livre or twelve deniers; one sou is to the livre as one shilling is to the pound. 

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