Obama has argued that the invasion was a bad idea (“Too Soon” 42), though he has acknowledged elsewhere that it led to much good (“A Stronger Country” 13).
In “Too Soon,” Obama argued that the invasion was a bad idea (42).
Photography, because it is both science and art, seems to be “a bridge discipline” (Barthes, “Of Loss and Cameras” 45).
Notice that when all three elements are used within the parenthetical citation, there is a comma added after the author’s name.

Obama has argued that the invasion was a bad idea (“Too Soon” 42), though he has acknowledged elsewhere that it led to much good (“A Stronger Country” 13).
Photography, because it is both science and art, seems to be “a bridge discipline” (Barthes, “Of Loss and Cameras” 45).