Where can I find the Latin conclusion of the prayers?

I was asked to celebrate the Mass in Latin for an international group of young people according to the ordinary form of the rite. We found in the sacristy the Missale Parvum where the text of the prayers of the Mass end only with the words “Per Dóminum”, “Qui vivis”, etc. Where can I find the rest of that conclusion?

The expansion of these conclusions can be found in the GIRM
(General Introduction of the Roman Missal),
under number 54 for the Collect prayer
and 77 for the prayer over the Offerings and the prayer after Communion:

54. […] In accordance with the ancient tradition of the Church,
the collect prayer is usually addressed to God the Father,
through Christ, in the Holy Spirit,[…]
and is concluded with a trinitarian ending, that is to say the longer ending,
in the following manner:

  • If the prayer is directed to the Father:
    Per Dóminum nostrum Iesum Christum Fílium tuum,
    qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus,
    per ómnia sǽcula sæculórum
    (Through our Lord, Jesus Christ,
    your Son, who lives and reigns with you and the Holy Spirit,
    one God, forever and ever);
  • If it is directed to the Father, but the Son is mentioned at the end:
    Qui tecum vivit et regnat in unitáte Spíritus Sancti, Deus,
    per omnia sǽcula sæculórum
    (Who lives and reigns with you and the Holy spirit, one God, forever and ever);
  • If it is directed to the Son:
    Qui vivis et regnas cum Deo Patre in unitáte Spíritus Sancti, Deus,
    per ómnia sǽcula sæculórum
    (You live and reign with God the Father in the unity of the Holy Spirit,
    one God, forever and ever).

77. […] In the Mass, only one Prayer over the Offerings is said,
and it ends with the shorter conclusion:
Per Christum Dominum nostrum
(Through Christ our Lord).
If, however, the Son is mentioned at the end of this prayer, the conclusion is:
Qui vivit et regnat in sǽcula sæculórum
(Who lives and reigns forever and ever).

For the prayer after Communion,
it is the same short conclusion as that of the prayer over de Offerings.

Try to have a copy of these texts on a piece of paper,
or in your agenda or smartphone,
until you know these by heart.