Question: What team won a two-leg Spanish football match played on 20 August and 23 August 1997, which one contestant won the 66th since its establishment, started on 31 August 1996 and finished on 23 June 1997?

full_context: Document 1: 1998–99 La Liga: The 1998–99 La Liga season, the 68th since its establishment, started on 29 August 1998 and finished on 20 June 1999.
Document 2: 1996–97 La Liga: The 1996–97 La Liga season, the 66th since its establishment, started on 31 August 1996 and finished on 23 June 1997.
Document 3: List of La Liga stadiums: Since the inception of La Liga in 1929, Spain's highest level of association football annual league tournament, 85 football stadiums have been used to host matches, with one more stadium set to host its first La Liga match in the 2016–17 season. The inaugural round of La Liga matches took place on 10 February 1929 with five clubs hosting the opening fixtures.
Document 4: 1997–98 La Liga: The 1997–98 La Liga season, the 67th since its establishment, started on 30 August 1997 and finished on 16 May 1998. On 29 March 1998, Sporting Gijón drew 0-0 with Real Zaragoza while Racing Santander, who were 19th in the table at the time, lost by Athletic Bilbao 4-3, to make Sporting Gijón the first team in La Liga history to be relegated in March, ending the season with a League record low points tally of just 13.
Document 5: 2008 Supercopa de España: The 2008 Supercopa de España was two-leg Spanish football matches played on 17 August and 24 August 2008. It was contested by Valencia, who were Spanish Cup winners in 2007–08, and Real Madrid, who won the 2007–08 La Liga. Real Madrid won 6–5 on aggregate for their eighth Supercopa de España title.
Document 6: 2014 Supercopa de España: The 2014 Supercopa de España was a two-legged football match-up played in August 2014 between the champions of 2013–14 La Liga, Atlético Madrid, and the winner of the 2013–14 Copa del Rey, Real Madrid. The first leg ended 1–1. Atlético won the trophy after beating Real Madrid 1–0 in second leg. This was the first time that the Supercopa de España was a Madrid derby, and also the first time since 2008 that the competition did not feature Barcelona team.
Document 7: 2015 Supercopa de España: The 2015 Supercopa de España was a two-legged football match-up that was played in August 2015 between Athletic Bilbao, runners-up of the 2014–15 Copa del Rey, and Barcelona, the champions of 2014–15 La Liga and the 2014–15 Copa del Rey. It was also a repetition of the 2015 Copa del Rey Final.
Document 8: 2015–16 La Liga: The 2015–16 La Liga football season (known as the "Liga BBVA" for sponsorship reasons) was the 85th since its establishment. Barcelona were the defending champions. It started on 21 August 2015 and concluded on 15 May 2016. Barcelona retained the title, winning it for the second consecutive season (their 24th Liga title) after beating Granada 3–0 on the final matchday.
Document 9: 2009 Supercopa de España: The 2009 Supercopa de España was two-legged Spanish football match-up played on 16 August and 23 August 2009. It was contested by Athletic Bilbao, the 2008–09 Copa del Rey runners-up, and Barcelona, the 2008–09 Primera División and 2008–09 Copa del Rey winners.
Document 10: 1996 Supercopa de España: The 1996 Supercopa de España was a two-leg Spanish football match played on 25 August and 28 August 1996. It was contested by FC Barcelona, who were Spanish Cup runners-up in 1995–96, and Atlético Madrid, who won the 1995–96 Spanish League and the 1995–96 Spanish Cup. FC Barcelona won 6–5 on aggregate.
Document 11: 1999 Supercopa de España: The 1999 Supercopa de España was a Spanish football competition, played over two legs on 8 August and 15 August 1999. It was contested by Valencia CF, who were Spanish Cup winners in 1998–99, and FC Barcelona, who won the 1998–99 Spanish League.
Document 12: 2017–18 La Liga: The 2017–18 La Liga season, also known as La Liga Santander for sponsorship reasons, is the 87th since its establishment. The season began on 18 August 2017 and is scheduled to conclude on 20 May 2018. The fixtures of the 2017–18 season were released on 21 July 2017.
Document 13: 1997 Supercopa de España: The 1997 Supercopa de España was a two-leg Spanish football match played on 20 August and 23 August 1997. The contestants were FC Barcelona, who were Spanish Cup winners in 1996–97, and Real Madrid, who won the 1996–97 Spanish League. Real Madrid won 5–3 on aggregate.
Document 14: 2007 Supercopa de España: The 2007 Supercopa de España was two-leg Spanish football matches played on 11 August and 19 August 2007. It contested by Sevilla, who were Spanish Cup winners in 2006–07, and Real Madrid, who won the 2006–07 Spanish League. Sevilla won 6–3 on aggregate.
Document 15: 2007–08 La Liga: The 2007–08 La Liga season, the 77th since its establishment, started on 25 August 2007 and finished on 18 May 2008. Real Madrid defended their La Liga title successfully after a 2–1 victory over Osasuna. This season, all European leagues ended earlier than the previous season, due to the UEFA Euro 2008 championship. It also was the first year of the new La Liga television agreement that had La Sexta mark its first year of television broadcasting.
ground_truth: Real Madrid