Duchesne, Louis Marie Olivier. XCIII Zacharias (741–752). Le Liber pontificalis; texte, introduction et commentaire par L. Duchesne (Volume 1). 1886. p. 426–439. Available on archive.org
bartleby.com
Reverend Alban Butler. «St. Zachary, Pope and Confessor». The Lives of the Saints, Volume 3. 1866. [3]
«according to historians, the main driving force of the Great Silk Road were not just Sogdians, but the carriers of a mixed Sogdian-Türkic culture that often came from mixed families.» Dybo A.V., Chronology of Türkic languages and linguistic contacts of early Türks, Moskow, 2007, p. 786. [2]
worldcat.org
Frank, Andre Gunder (2008). «El carrusel del comercio global 1400-1800». Re-Orientar: la economía global en la era del predominio asiático (Pablo Sánchez León, trad.). Valencia: Publicacions de la Universitat de Valencia (PUV). ISBN978-84-370-7151-0. OCLC733795286.