PURPOSE: To discriminate immediately places where desired books and articles are received by transmitting a code signal representing classification from a transmitter with weak radio wave to be received by a receiver provided on a rack.

CONSTITUTION: Each receiving device 3 has a display unit 5 constituted from a receiver 4 and a luminescent element such as luminescent diode. A transmitting device 6 for transmitting a classification number signal to the each receiving device 3 is formed into a compact portable one which has a control switch 7 for indicating the classification number constituted from a ten key board from 0 to 9 or the like, a transmitter 8 for transmitting the classification number indicated by the control switch 7 with weak FM modulated wave carrying said number and an antenna 9 for transmitting this signal. Usually, the classification of books represents kind by the order of 100, class by the order of 10 and item by the order of 1. The classification represents subitems lower than said item by numerals below decimal point. Thus, for example in the case of publications concerning pedagogy, 371 will do which is indicated by the ten key board.