Poulle, Emmanuel; de Verdun, Bernard (1964). "Bernard de Verdun et le turquet". Isis. 55 (2): 200–208. doi:10.1086/349829. JSTOR228186.
Thorndike, Lynn (October 1945). "Franco de Polonia and the Turquet". Isis. 36 (1): 6–7. doi:10.1086/347897. JSTOR225669.
Dekker, Elly; Kristen Lippincott (1999). "The Scientific Instruments in Holbein's Ambassadors: A Re-Examination". Journal of the Warburg and Courtauld Institutes. 62. The Warburg Institute: 93–125. doi:10.2307/751384. ISSN0075-4390. JSTOR751384.
Poulle, Emmanuel; de Verdun, Bernard (1964). "Bernard de Verdun et le turquet". Isis. 55 (2): 200–208. doi:10.1086/349829. JSTOR228186.
Thorndike, Lynn (October 1945). "Franco de Polonia and the Turquet". Isis. 36 (1): 6–7. doi:10.1086/347897. JSTOR225669.
Dekker, Elly; Kristen Lippincott (1999). "The Scientific Instruments in Holbein's Ambassadors: A Re-Examination". Journal of the Warburg and Courtauld Institutes. 62. The Warburg Institute: 93–125. doi:10.2307/751384. ISSN0075-4390. JSTOR751384.
Dekker, Elly; Kristen Lippincott (1999). "The Scientific Instruments in Holbein's Ambassadors: A Re-Examination". Journal of the Warburg and Courtauld Institutes. 62. The Warburg Institute: 93–125. doi:10.2307/751384. ISSN0075-4390. JSTOR751384.