GRAMMAR To refer to someone or something that belongs to or is connected with someone, it is usual to use -'s or -s' (NOT of) with short noun phrases : Dad's car (NOT the car of Dad) | a child's bike (NOT the bike of a child) | my sister's boyfriend (NOT the boyfriend of my sister) | the miners' strike (NOT the strike of the miners) When referring to one of several people or things belonging to or connected with someone, or when using 'this' or 'that', use of + mine/yours/his/hers/ours/theirs : a friend of mine (NOT a friend of me) | a relation of ours (NOT a relation of us) | that car of yours (NOT that car of you) To talk about the person who sang, wrote, painted, or composed a particular work, use by not of : a song by Mariah Carey (NOT of Mariah Carey)