Problems in operations research : principles and solutions 2026-02-15T21:16:06+03:00 DEBUG: VuFind\ILS\Driver\Folio: Token taken from global cache: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiO... - Gupta, Prem Kumar; Hira, D. S. (S. Chand, 1991)