Question: The Men's 1991 World Amateur Boxing Championships were organized by which Olympic-style boxing body?

Context paragraphs:
William Irwin (boxer): William "Billy" 'The Kid' Irwin ( (1968--) 20 1968 (age (2017)-(1968)-((11)<(05)or(11)==(05)and(29)<(20)) ) ) born Niagara Falls, Ontario, is a retired Canadian amateur lightweight and professional light/light welter/welterweight boxer of the 1990s and 2000s who as an amateur won a bronze medal in the Boxing at the 1991 Pan American Games in Havana, Cuba, losing to eventual silver medal winner Patrice Brooks of the United States, represented Canada at the 1991 World Amateur Boxing Championships in Sydney, Australia losing to Julien Lorcy of France, and represented Canada at the 1992 Summer Olympics in Barcelona, Spain, he was stopped in the second round of the lightweight division (– 60 kg) by Ronald Chavez of the Philippines, and as a professional won the Canadian Professional Boxing Council (CPBC) lightweight title, Canada lightweight title, International Boxing Organization (IBO) lightweight title, World Boxing Council (WBC) Continental Americas lightweight title, and Commonwealth lightweight title, and was a challenger for the International Boxing Federation (IBF) lightweight title against Paul Spadafora, and World Boxing Association (WBA) World lightweight title against Juan Díaz, his professional fighting weight varied from 133+1/2 lb , i.e. lightweight to 142 lb , i.e. welterweight.  He retired from boxing after losing to Juan Diaz in 2005, his second unsuccessful world title challenge.  His final record was 42(30)–6–0.

AIBA World Boxing Championships: The AIBA World Boxing Championships and the AIBA Women's World Boxing Championships are biennial amateur boxing competitions organised by the International Boxing Association (AIBA), which is the sport governing body.  Alongside the Olympic boxing programme, it is the highest level of competition for the sport.  The championships was first held in 1974 Havana, Cuba as a men's only event and the first women's championships was held over 25 years later in 2001.  Formerly known as the World Amateur Boxing Championships and the Women's World Amateur Boxing Championships, the men's and women's competitions are held separately and since 2006 the biennial championships have been held in alternating years.

International Boxing Association (amateur): The International Boxing Association, originally the Association Internationale de Boxe Amateur and still referred to as the AIBA is a sport organization that sanctions amateur (Olympic-style) boxing matches and awards world and subordinate championships.  Recently, AIBA has been trying to build its own professional version of boxing, where boxers would retain their Olympic eligibility, through the team tournament league known as World Series of Boxing and AIBA Pro Boxing.

1998 Junior World Boxing Championships: The 1998 Junior World Boxing Championships were held in Buenos Aires, Argentina, from November 6 to November 16, 1998.  It was the tenth edition of the Junior World Boxing Championships.  The competition is under the supervision of the world's governing body for amateur boxing AIBA and is the junior version of the World Amateur Boxing Championships.

1991 World Amateur Boxing Championships: The Men's 1991 World Amateur Boxing Championships were held in Sydney, Australia, from November 15 to 23.  The sixth edition of this competition, held nearly a year before the Summer Olympics in Barcelona, Spain, was organised by the world's governing body for amateur boxing, AIBA.

2012 AIBA Youth World Boxing Championships: The 2012 AIBA Youth World Boxing Championships were held in Yerevan, Armenia, from November 25 to December 8, 2012.  The competition is under the supervision of the world's governing body for amateur boxing AIBA and is the junior version of the World Amateur Boxing Championships.  Boxers aged between 17 and 18 as of 1 January 2013 were eligible to compete.

2010 AIBA Youth World Boxing Championships: The 2010 AIBA Youth World Boxing Championships were held in Baku, Azerbaijan, from April 25 to May 3, 2010.  It was the second edition of the AIBA Youth World Boxing Championships which had taken over from the Junior World Championship.  The competition is under the supervision of the world's governing body for amateur boxing AIBA and is the junior version of the World Amateur Boxing Championships.

Ercüment Aslan: A member of the Turkey national boxing team since 1988, Ercument’s amateur career record was 175-25.  Highlights include being the Junior world amateur champion in Istanbul in 1994, 3rd at the 1997 World Amateur Boxing Championships in Budapest in 1997 and 2nd at the 1998 European Amateur Boxing Championships.  Unfortunately an injury at the World Amateur Championships in Houston in 1999 caused him to miss out on selection for the 2000 Olympic Games.  He had a successful professional career with 8 wins and 2 losses.

2014 AIBA Youth World Boxing Championships: The 2014 AIBA Youth World Boxing Championships were held in Sofia, Bulgaria, from April 10 to April 25, 2014.  The competition is under the supervision of the world's governing body for amateur boxing AIBA and is the junior version of the World Amateur Boxing Championships.  Boxers aged between 17 and 18 as of 1 January 2015 were eligible to compete.

2008 AIBA Youth World Boxing Championships: The 2008 AIBA Youth World Boxing Championships were held in Guadalajara, Mexico, from October 31 to November 1, 2008.  It was the first edition of the AIBA Youth World Boxing Championships which had taken over from the Junior World Championship.  The competition is under the supervision of the world's governing body for amateur boxing AIBA and is the junior version of the World Amateur Boxing Championships.

Supporting paragraphs: 1991 World Amateur Boxing Championships International Boxing Association (amateur)
Answer: International Boxing Association