Personal names can be in the genitive case, too. For "John's son", the Irish is "mac Sheáin" (mahk HYAW*-in), son of John. "James' book" is "leabhar Shéamais" (LOU-uhr HAY*-mish). Where possible, aspirate an initial consonant in a name used in this way. With all masculine names except "Liam" (LEE-uhm), make a final consonant in the genitive case slender. To show the need for a slender sound in pronunciation, write an "i" before the final consonant. With feminine names, merely aspirate the initial consonant where possible. Learn these as examples that you can readily recall in working with new names:
Nearly all feminine names end in a slender consonant or a vowel, and so the ending does not usually change. "Bríd" is one that does change. "Leabhar Bhríde" (VREED-e) is "Bridget's book".
To say "a book of John's" or "one of John's books", the form is "leabhar le Seán", literally "book with John". Here, the person's name does not change.