You can find and borrow older, digitized versions of the catalogue for free through the Internet Archive . These include historical editions such as the 2009 Volume 3 and specialized volumes for French Colonies Free Online Substitutes:
A free online catalogue specifically for French stamps that includes Yvert numbering. StampsFrance catalogue stamps yvert et tellier free download pdf
A comprehensive online database covering stamps from the 1920s to the present, often listing Yvert numbers for items currently on sale. Philatelie.fr You can find and borrow older, digitized versions
Offers free data for stamps issued up to 1990, including Yvert and Scott references. Internet Archive Paid Digital & Print Alternatives You can find and borrow older