Leonardo Da Vinci. www.encyclopedia.com. (Hozzáférés: 2023. augusztus 19.)
Leonardo Da Vinci | Encyclopedia.com. www.encyclopedia.com. (Hozzáférés: 2023. augusztus 19.) „After completing his apprenticeship, Leonardo stayed on as an assistant in Verrocchio's shop, and his earliest known painting is a product of his collaboration with the master.”
Leonardo da Vinci's Notebooks Get Digitized: Where to Read the Renaissance Man's Manuscripts Online (amerikai angol nyelven). Open Culture. (Hozzáférés: 2023. augusztus 19.) „Totaling some 13,000 pages of notes and drawings, they record something of every aspect of the Renaissance man’s intellectual and daily life: studies for artworks, designs for elegant buildings and fantastical machines, observations of the world around him, lists of his groceries and his debtors.”