In either manual or conrputer-based systems, we cannot expect efiicient retrieval of technical information without an efficient indexing method with good indexing tools. The royal road to good search strategy is to use a concrete indexing method and make the most efficient use of classification and indexing tools, such as UDC and controlled keywords. The author, on basis of his own use of UDC, suggests a good indexing method using UDC jointly with keywords so as to avoid the demerits of UDC alone. The author introduces an indexing method that uses both the UDC numbers and controlled keywords to complement each other's function for efficient information retrieval.