I want to know the answer to the following question:
Whose earlier work did Nicholas Vavilov build upon?
All the background I'm provided with is that "Building on the extensive earlier work of Alphonse de Candolle, Nikolai Vavilov (1887–1943) produced accounts of the biogeography, centres of origin, and evolutionary history of economic plants.". Is that enough to answer the question?
Answer: yes