“…Five main aspects defined in the order-picking process were included in 73 studies on implementing the combined planning process problem. Nineteen studies did not study these five categories and solely focused on ergonomics, cost, equipment, and storage space [2,4,6,9,28,32,56,57,63,65,66,68,69,[72][73][74][75][76][77]. Therefore, we can state that only 20% of the reviewed studies did not focus on the five main categories of research, indicating the importance of assignment, routing, batching, sequencing, and tardiness in the order-picking process.…”