Question: What were revised between 1951 and 1955?
Sentence: After the Vatican Council, in April 1969, Paul VI approved the "new Order of Mass" promulgated in 1970, as stated in the Acta Apostolica Sedis to "end experimentation" with the Mass and which included the introduction of three new Eucharistic Prayers to what was up to then a single Roman Canon.
Answer in sentence: no