ਵਾਲਟਰ ਸਤਾਰਕੀ, The Road to Santiago (1957) John Murray, reprinted 2003.
↑ Kent, William H. (1913). "Indulgences". Catholic Encyclopedia. New York: Robert Appleton Company. . This entry on indulgences suggests that the evolution of the doctrine came to include pilgrimage to shrines as a trend that developed from the eighth century A.D.: "Among other forms of commutation were pilgrimages to well-known shrines such as that at St. Albans in England or at Compostela in Spain. But the most important place of pilgrimage was Rome. According to Bede (674-735) the visitatio liminum, or visit to the tomb of the Apostles, was even then regarded as a good work of great efficacy (Hist. Eccl., IV, 23). At first the pilgrims came simply to venerate the relics of the Apostles and martyrs; but in course of time their chief purpose was to gain the indulgences granted by the pope and attached especially to the Stations."
↑ "Holy Years at Santiago de Compostela". Retrieved March 6, 2014.