You write the Gb in the base; no chord members must be doubled because it's a seventh chord. To spell the rest of the chord you would find common tones between the last chord and the current tones (If the soprano had G in the previous chord give the soprano G in this chord). Once you've found your common tones, you'd then find close tones (if the tenor had Eb in the last chord give him D in this one). You then give the remaining chord member to the last part.
If you're asking who, then there are several answers. Maya Angelou, Joan Baez, Harry Belafonte, Bob Dylan, Mahalia Jackson, Pete Seeger, Otetta Holmes, etc.
