Question: Our World included the opera singer best known for what technique?

Context paragraphs:
Richard White (actor): Richard White is an American actor and opera singer best known for voicing the character of Gaston in Disney's "Beauty and the Beast" and in the TV series "House of Mouse".

Gioconda Vessichelli: Gioconda Vessichelli (born in Rome, Italy) is an opera singer.  Gioconda is the inventor and pioneer of BollywoOPERA style.  She has sung in the Bollywood movie "Prague "in 2013, and she has given her voice for the Bollywood movie "Mary Kom" on the song "Ziddi dil" together with Vishal Dadlani.On 19th May 2017 her song "Itni si baat hai" has been released by the label T-series.  On 20 December 2014 the song "Thodi Daaru" was released featuring Mika Singh.  Gioconda has done live performances as first fusion ever between opera and classical Hindi music with artists of the caliber of Grammy Award winner Sukhwinder Singh, Hari Haran, Gino Banks, Niladri Kumar, Silvaganesha, in festivals and auditoriums like Nehru Centre[20] in Mumbai.  She collaborates with Anup Jalota, and many others.  On 31 March 2016 her international video "We are one" in which she sings and acts together with Anup Jalota for peace in the world has been launched from the Minister of India in Delhi.  She is in the annual book of Italian opera singer for having sung in the first world edition of contemporary opera at "Teatro comunale di Modena", broadcast on Italian state radio RAI.  Gioconda is the first singer in the premiere world ever of the contemporary opera “Lavinia fuggita” by Matteo d’Amico.  She has two degrees in opera singing and musicology from Italian conservatory "Santa Cecilia" and international high school of opera "H.Wolf".  The tenor Luciano Pavarotti has been her teacher, among other opera singers who selected her as one of the best students.  She was selected as best singer at accademia rossiniana in Pesaro and she debuts the role of "Madama cortese" in "il viaggio a Reims" by Rossini with the symphonic orchestra of Rof at Rossini theatre in Pesaro.  She sings again in a Rossini opera at Ercolano international opera season in "Il barbiere di Siviglia" and at teatro Politeama opera season in Lecce.  After Rossini she debuts "Carmen" by Bizet.  Her interpretation of the role "Mimì" in the opera "La Boheme" by Puccini received positive critiques.

Derek Hammond-Stroud: Derek Hammond-Stroud, OBE (10 January 192614 May 2012) was an English baritone opera singer best known for his performances of German lieder and his international performances in opera, particularly the roles of Alberich in Wagner's "Der Ring des Nibelungen", Herr Faninal in "Der Rosenkavalier" and Beckmesser in "Die Meistersinger von Nürnberg".  He also made recordings, including a series of recordings of the Gilbert and Sullivan patter roles.

Helen Donaldson: Helen Donaldson (born 14 March 1968 in Rockhampton, Queensland) is an Australian opera singer best known for her performances of the heroines in Gilbert and Sullivan operas.

Huang Shixiang: Huang Shixiang is a Chinese Beijing opera singer best known for his performances in "Jade River" "Taijun Cichao" (太君辭朝) and "Hongzong Liema" (紅鬃烈馬).  His father, Pugong, was the son of Zaixun, a Manchu prince of the late Qing dynasty.  His mother, Xueyanqin (or Huang Yongni), was also a famous Beijing opera actress.

Our World (TV special): Our World was the first live, international, satellite television production, which was broadcast on 25 June 1967.  Creative artists, including The Beatles, opera singer Maria Callas, and painter Pablo Picasso—representing nineteen nations—were invited to perform or appear in separate segments featuring their respective countries.  The two-and-half-hour event had the largest television audience ever up to that date: an estimated 400 to 700 million people around the globe watched the broadcast.  Today, it is most famous for the segment from the United Kingdom starring the Beatles.  They performed their song "All You Need Is Love" for the first time to close the broadcast.

Vladimir Fontikov: Vladimir Karnikovich Fontikov (May 17, 1941 – October 12, 1987) was a Soviet opera singer best known for his interpretation of Modest Mussorgsky's "Boris Gudunov".

Frederick Federici: Frederick Federici (22 April 1850 – 3 March 1888) was an Italian-born British opera singer best known for his work in early performances of the Savoy Operas written by Gilbert and Sullivan.  Early in his career, Federici also worked as a talent agent and wrote songs before becoming a concert singer.

Maria Callas: Maria Callas, Commendatore OMRI (Greek: Μαρία Κάλλας ; December 2, 1923 – September 16, 1977), was a Greek-American soprano, and one of the most renowned and influential opera singers of the 20th century.  Many critics praised her "bel canto" technique, wide-ranging voice and dramatic interpretations.  Her repertoire ranged from classical "opera seria" to the "bel canto" operas of Donizetti, Bellini and Rossini and further, to the works of Verdi and Puccini; and, in her early career, to the music dramas of Wagner.  Her musical and dramatic talents led to her being hailed as "La Divina".

Elisabetta Manfredini-Guarmani: Elisabetta Manfredini-Guarmani (2 June 1780 – after 1828) was an Italian opera singer best known for having created the leading soprano roles in four of Rossini's operas, roles which he wrote specifically for her voice.  She was born Antonia Elisabetta Manfredini in Bologna and was the daughter of the composer and music theorist Vincenzo Manfredini.  After her stage debut in 1810 when she sang in the premiere of Stefano Pavesi's "Il trionfo di Gedeone" at Bologna's Teatro del Corso, she went on to perform at La Fenice, La Scala, Teatro Regio di Torino, Rome's Teatro Argentina and several other opera houses, primarily in Northern Italy.  In addition to the roles she created in Rossini's operas, she also sang in the world premieres of operas by several composers who are lesser known today, including Pietro Raimondi, Simon Mayr, and Ferdinando Paër.  Her last known appearance was in 1828 after which there is no further trace of her.  The date and place of her death are unknown.

Supporting paragraphs: Our World (TV special) Maria Callas
Answer: bel canto