see more

UNITED STATES - JANUARY 01: USA Photo of DOOBIE BROTHERS (Photo by Richard E. Aaron/Redferns)

UNITED STATES - JANUARY 01:  USA  Photo of DOOBIE BROTHERS  (Photo by Richard E. Aaron/Redferns)

see more

UNITED STATES - JANUARY 01: (AUSTRALIA OUT) USA Photo of DOOBIE BROTHERS, (Photo by GAB Archive/Redferns)

UNITED STATES - JANUARY 01:  (AUSTRALIA OUT) USA  Photo of DOOBIE BROTHERS,    (Photo by GAB Archive/Redferns)

see more

UNITED STATES - JANUARY 01: USA Photo of DOOBIE BROTHERS (Photo by Richard E. Aaron/Redferns)

UNITED STATES - JANUARY 01:  USA  Photo of DOOBIE BROTHERS  (Photo by Richard E. Aaron/Redferns)

see more

SAN FRANCISCO - 1975: Keith Knudsen of The Doobie Brothers performs live at The Winterland Ballroom in 1975 in San Francisco, California. (Photo by Richard McCaffrey/ Michael Ochs Archive/ Getty Images)

SAN FRANCISCO - 1975:  Keith Knudsen of The Doobie Brothers performs live at The Winterland Ballroom in 1975 in San Francisco, California. (Photo by Richard McCaffrey/ Michael Ochs Archive/ Getty Images)

see more

UNSPECIFIED - JANUARY 01: Photo of DOOBIE BROTHERS (Photo by Richard E. Aaron/Redferns)

UNSPECIFIED - JANUARY 01:  Photo of DOOBIE BROTHERS  (Photo by Richard E. Aaron/Redferns)