Christine E. Gudorf. Catholic Social Teaching on Liberation Themes (1981) 75. "The efficacy of the Word was clearly not doubted by Pius XI. The solution to social problems lay not in attention to them, but in the religious renewal implied in a return to the Gospel and the Church. There is an implicit idealism underlying most of Pius' writings, a belief that right belief is primary. This is idealism, the direct opposite of Marxist materialism. It is a preference to work with ideas rather than material reality in the consideration of theology and social problems."
Donal Dorr. Option for the Poor (1983) 74. "Pius XI... takes a 'prophetic' stand on political and economic questions. His stand shows that the role played by the Church in society does not always have to be a conservative one. Concern for stability is important; but stability is not the only social value, or even the highest. Justice ranks higher. There may be times when the value of justice calls the Christian community and its leaders to take risks--not merely personal risks but what might be called 'social risks.' They may feel called to challenge the basic economic and political structures which seem necessary for the survival of our society--and even for the world as we know it."
Dorr, Donal. Option for the Poor. Maryknoll: Orbis, 1983, pp. 57-75.
Hennesey, James, S.J. "Pius XI." Judith A. Dwyer, ed., The New Dictionary of Catholic Social Thought, Collegeville, MN: Liturgical Press, 1994, pp. 739-41.
McLaughlin, Terence P., C.S.B. "Introduction." The Church and the Reconstruction of the Modern World: The Social Encyclicals of Pius XI. Garden City, NY: Image Books, 1957, pp. 4-23