Styled a "festa teatrale", "Le feste d'Apollo" consists of a prologue and three self-contained acts on the model of French "opéra-ballet" (the court of Parma was passionately interested in French culture).
 Gluck knew the Archduchess Maria Amalia well as she had sung in two of his operas, "Il Parnaso confuso" and "La corona", in Vienna.
 The composer recycled a lot of music from his earlier operas in the score of "Le feste".
 In fact, the whole of the third act, "Orfeo", is a shorter reworking of his most famous piece, "Orfeo ed Euridice" (1762).
 The overture to the prologue is taken from "Telemaco".
 Gluck later reused some of the choruses in two of the operas he wrote for Paris, "Iphigénie en Aulide" and "Iphigénie en Tauride".
Orpheus is a symphonic poem written by Franz Liszt in 1853-4.
 He numbered it No. 4 in the cycle of 12 he wrote during his time in Weimar, Germany.
 It was first performed on 16 February 1854, conducted by the composer, as an introduction to the first Weimar performance of Christoph Willibald Gluck's opera "Orfeo ed Euridice".
 The performance helped celebrate the birthday of Weimar's Grand Duchess Maria Pavlovna, who was an amateur musician and a staunch supporter of Liszt at Weimar.
Don Juan ou Le Festin de Pierre (Don Juan, or the Stone Guest's Banquet) is a ballet with a libretto by Ranieri de' Calzabigi, music by Christoph Willibald von Gluck, and choreography by Gasparo Angiolini.
 The ballet's first performance was in Vienna, Austria on Saturday, 17 October 1761, at the Theater am Kärntnertor.
 Its innovation in the history of ballet, coming a year before Gluck's radical reform of "opera seria" with his "Orfeo ed Euridice" (1762), was its coherent narrative element, though the series of conventional "divertissement" dances in the second act lies within the well-established ballet tradition of an "entr'acte" effecting a pause in the story-telling.
 The ballet follows the legend of Don Juan and his descent into Hell after killing his "inamorata's" father in a duel.
Paride ed Elena (] ; "Paris and Helen") is an opera by Christoph Willibald Gluck.
 It is the third of Gluck's so-called reform operas for Vienna, following "Alceste" and "Orfeo ed Euridice", and the least often performed of the three.
 Like its predecessors, the libretto was written by Ranieri de' Calzabigi.
 The opera tells the story of the events between the Judgment of Paris and the flight of Paris and Helen to Troy.
 It was premiered at the Burgtheater in Vienna on 3 November 1770.
Wilhelmine Ritter was a German operatic mezzo-soprano.
 Little is known about the artist and the details about her birth and training are unknown.
 She was a member of the Bavarian State Opera in Munich from 1866 through 1871.
 While there she notably created the roles of Flosshilde in Richard Wagner's "Das Rheingold" on 22 September 1869 and Grimgerde (one of the Valkyries) in Wagner's "Die Walküre" on 26 June 1869.
 Her last performance at the house was as Orfeo in Christoph Willibald Gluck's "Orfeo ed Euridice" in 1871.
 She got married soon after and retired permanently from the stage.
 Currently no further biographical details about Ritter have surfaced.
Königskinder (German for "The King's Children") is a stage work by Engelbert Humperdinck that exists in two versions: as a melodrama and as an opera or more precisely a "Märchenoper".
 The libretto was written by Ernst Rosmer (pen name of Else Bernstein-Porges), adapted from her play of the same name.
The following discography for Gluck's opera "Orfeo ed Euridice" is mainly based on the research of Giuseppe Rossi, which appeared in the programme notes to the performance of the work at the 70th Maggio Musicale Fiorentino in 2007, under the title "Discografia – Christoph Willibald Gluck – Orfeo ed Euridice (Orphée et Eurydice)".
 Rossi's data has been checked against the sources referenced in the notes.
Pierre-Louis Moline (  1740 – 20 March 1820) was a prolific French dramatist, poet and librettist.
 His play "La Réunion du six août" was one of the longest-running patriotic pieces during the time of the French Revolution with 52 performances at the Paris Opéra.
 He also wrote the epitaph for the tomb of Jean-Paul Marat.
 However, he is best remembered today for having adapted Calzabigi's libretto for Gluck's "Orphée et Euridice" (a reworked version of his "Orfeo ed Euridice").
L'anima del filosofo, ossia Orfeo ed Euridice ("The Soul of the Philosopher, or Orpheus and Euridice"), Hob.
 28/13, is an opera in Italian in four acts by Joseph Haydn, the last he ever wrote.
 The libretto, by Carlo Francesco Badini, is based on the myth of Orpheus and Euridice as told in Ovid's "Metamorphoses".
 Composed in 1791, the opera was never performed during Haydn's lifetime.
Orfeo ed Euridice (French version: Orphée et Eurydice ; English: "Orpheus and Eurydice") is an opera composed by Christoph Willibald Gluck based on the myth of Orpheus, set to a libretto by Ranieri de' Calzabigi.
 It belongs to the genre of the "azione teatrale", meaning an opera on a mythological subject with choruses and dancing.
 The piece was first performed at the Burgtheater in Vienna on 5 October 1762 in the presence of Empress Maria Theresa.
 "Orfeo ed Euridice" is the first of Gluck's "reform" operas, in which he attempted to replace the abstruse plots and overly complex music of "opera seria" with a "noble simplicity" in both the music and the drama.

Question: Orfeo ed Euridice and Königskinder, are which type of performance?
Answer: opera