. "Knebworth Festival" . . "Knebworth" . "1979 Knebworth Festival" . "Led Zeppelin in 1979 (two concerts)" . . "Knebworth in 1979" . . "concerts at Knebworth in 1979" . "1979" . . . . . "Knebworth Festival 1979" . "Knebworth Concerts" . . "Knebworth Concert" . "shows at Knebworth" . . "Knebworth 1979" . . . . "two concerts" . "Knebworth Festival 1979" . . . "Knebworth Music Festival" . "Knebworth Festival in 1979" . "1979 concerts" .