By Carey Publications Ltd, S M Houghton
By Horton, Michael Scott
By William Barclay
By liguori-publications-and-libreria-editrice-vaticana
By Duffy, Eamon
By Catholic Church
By Macleod, Donald
By Williamson, G. I.
By John Hardon
By Bowring, Kelly
By Myers, Benjamin
By Johnson, Luke Timothy
By Pannenberg, Wolfhard
By MacGregor, Geddes
By Vincent, Thomas
By Joseph Ratzinger, Cardinal Christoph Schonborn
By Saint Thomas Aquinas
By Cardinal Christoph Schonborn
By Leo J. Trese
By Peter J. Kreeft
By Evelyn Underhill (http://evelynunderhill.org/)
By Francis J Ripley
By James Tolhurst
By World Council of Churches, Faith and Order Commission
By Rosalie Curtin, etc.
By John Burnaby
By Redemptorists