The Electric Light Orchestra (ELO) are an English rock band formed in Birmingham in 1970, by songwriters/multi-instrumentalists Jeff Lynne and Roy Wood with drummer Bev Bevan. Their music is characterised by a fusion of Beatlesque pop, classical arrangements, and futuristic iconography. After Wood's departure in 1972, Lynne became the band's leader, arranging and producing every album while writing virtually all of their original material. For their initial tenure, Lynne, Bevan and keyboardist Richard Tandy were the group's only consistent members.

For the next six years, Harvest and Epic/Legacy reissued ELO's back catalogue. Included amongst the remastered album tracks were unreleased songs and outtakes, including two new singles. The first was "Surrender" which registered on the lower end of the UK Singles Chart at number 81, some 30 years after it was written in 1976. The other single was "Latitude 88 North". On 9 August 2010, Eagle Rock Entertainment released Live - The Early Years in the UK as a DVD compilation that included Fusion - Live in London (1976) along with never before released live performances at Brunel University (1973) and on a German TV show Rockpalast (1974). The US had a slightly edited release on 24 August 2010. The Essential Electric Light Orchestra artwork was re-jigged to feature two different covers. The US and Australian releases shared one design, while the rest of the world featured the other for a new double album release in October 2011. Mr. Blue Sky: The Very Best of Electric Light Orchestra was released on 8 October 2012. It is an album of new recordings of ELO's greatest hits by Lynne; along with a new song "Point of No Return", released to coincide with Lynne's second solo album release Long Wave. These new 2012 albums contained advertisement cards, announcing the re-release of expanded and remastered versions of both the 2001 album Zoom and Lynne's debut solo album Armchair Theatre, originally released in 1990. Both albums were re-released in April 2013 with various bonus tracks. Also released was the live album, Electric Light Orchestra Live, showcasing songs from the Zoom tour. All three releases also featured new studio recordings as bonus tracks. Lynne and Tandy reunited again on 12 November 2013 to perform, under the name Jeff Lynne and Friends, "Livin' Thing" and "Mr Blue Sky" at the Children in Need Rocks concert at Hammersmith Eventim Apollo, London. The backing orchestra was the BBC Concert Orchestra, with Chereene Allen on lead violin.

Answer the following question by taking a quote from the article: what albums or songs were in the back catalogue?
Included amongst the remastered album tracks were unreleased songs and outtakes, including two new singles.