Is the form with apostrophe 's' definitively the only correct version? If so, do you have a link? In general, opinion seems to be divided as to whether the pos

Is the form with apostrophe 's' definitively the only correct version? If so, do you have a link? In general, opinion seems to be divided as to whether the possessive form of a singular noun ending in 's' takes an apostrophe 's' or just an apostrophe: https://en.wikipedia.org/wiki/Apostrophe#Singular_nouns_ending_with_an_.22s.22_or_.22z.22_sound https://en.wikipedia.org/wiki/Apostrophe#Singular_nouns_endi...