Tantum Ergo is the incipit of the last two verses of "Pange Lingua", a Medieval Latin hymn written by St Thomas Aquinas c. 1264.
 The "Genitori Genitoque" and "Procedenti ab Utroque" portions are adapted from Adam of Saint Victor's sequence for Pentecost.
 The hymn's Latin incipit literally translates to “Therefore so great.”
Tantum ergo ("Let us raise"), WAB 32, is the first of eight settings of the hymn "Tantum ergo" composed by Anton Bruckner in 1845.
Josef Anton Bruckner (] ; (1824--)04 1824 (1896--)11 1896 ) was an Austrian composer best known for his symphonies, masses, and motets.
 The first are considered emblematic of the final stage of Austro-German Romanticism because of their rich harmonic language, strongly polyphonic character, and considerable length.
 Bruckner's compositions helped to define contemporary musical radicalism, owing to their dissonances, unprepared modulations, and roving harmonies.
O salutaris Hostia (Latin, "O Saving Victim" or "O Saving Sacrifice"), is a section of one of the Eucharistic hymns written by St Thomas Aquinas for the Feast of Corpus Christi.
 He wrote it for the Hour of Lauds in the Divine Office.
 It is actually the last two stanzas of the hymn "Verbum supernum prodiens", and is used for the Adoration of the Blessed Sacrament.
 The other two hymns written by Aquinas for the Feast contain the famous sections "Panis angelicus" and "Tantum ergo".
Pange Lingua Gloriosi Corporis Mysterium is a Medieval Latin hymn written by Saint Thomas Aquinas (1225–1274) for the Feast of Corpus Christi.
 It is also sung on Maundy Thursday during the procession from the church to the place where the Blessed Sacrament is kept until Good Friday.
 The last two stanzas (called, separately, "Tantum Ergo)" are sung at Benediction of the Blessed Sacrament.
 The hymn expresses the doctrine that the bread and wine are changed into the Body and Blood of Christ during the celebration of the Eucharist.
Luigi Lamberti (22 October 1769 – after 1812) was an Italian composer of operas and other pieces.
 He was born in Savona and, like Francesco Gnecco, he studied with Mariani, the "maestro di capella" of the Savona cathedral.
 Once his master died, he succeeded to the position.
 However, he was said to be of a "restless spirit" and abandoned the position.
 Moving to Paris in 1806, he published a number of compositions dedicated to princess Pauline Bonaparte.
 In Italy, he composed the operas "Orfeo" (1796), "L' Amante Schernito", and "I Due Fratelli Originali".
 He was prolific.
 He also composed various masses; vespers and hymns including two "Tantum ergo" and a "Miserere"; motets; concertos for three, four and five strings; and symphonies, among them are two titled "Pubblio Claudio" and "The Death of Louis XVI".
 While he lived in Paris in 1812, it is not known what became of him afterward.
Tantum ergo ("Let us raise"), WAB 44, is the last of eight settings of the hymn "Tantum ergo" composed by Anton Bruckner in  1854 .
The four Tantum ergo ("Let us raise"), WAB 41, are settings of the hymn "Tantum ergo" composed by Anton Bruckner in 1846.
Tantum ergo ("Let us raise"), WAB 43, is the second of eight settings of the hymn "Tantum ergo" composed by Anton Bruckner in  1845 .
Tantum ergo ("Let us raise"), WAB 42, is a setting of the hymn "Tantum ergo" composed by Anton Bruckner in 1846.

Question: The four Tantum ergo are settings of the hymn "Tantum ergo" composed by a composer of what nationality?
Answer: Austrian