The previously unreleased covers have been released today on digital platforms and on a very limited number of 7" vinyl to mark what would've been Bowie's 74th birthday.

Bowie recorded his cover of Lennon's "Mother" in 1997 and '98 between Bermuda and Sound On Sound Studios in New York. It was produced by Bowie and Tony Visconti and was intended for a Lennon tribute that never ended up happening.

His version of Dylan's "Tryin' To Get To Heaven" was captured at Looking Glass in New York City in 1998.

Later today Anna Calvi, Duran Duran, Atticus Ross, Trent Reznor, Billy Corgan, Boy George, Taylor Momsen and more will take part in the tribute livestream event, A Bowie Celebration: Just For One Day!. It'll start at 6pm PT / 2am GMT today (8 January), and tickets are available to buy now from rollinglivestudios.com.

David Bowie's "Mother / Tryin' To Get To Heaven" covers and limited 7" vinyl is out now via Parlophone/ISO Records.