In 1913 Ford W. Harris published a paper with the title “How Many Parts to Make at
Once” (Harris, 1913). This paper addresses the problem of finding the most economical
quantity to be made of each lot of a product so as to meet a demand that continues over
time at a constant rate. His derivation of the square-root formula for this quantity is a
foundation result in operations research and the theory of inventory management, which
is commonly known as the “economic order quantity” (EOQ)