A display screen including a first display area displaying plural similar medical images received from a case search system and a second display area displaying disease names is displayed on a display of an information terminal. Each similar medical image is a medical image contained in an electronic medical book, and has additional information which includes the number of a page containing the similar medical image. If the user's selection of a similar medical image is detected for the first time after the display of the display screen, a page of an electronic medical book containing the selected similar medical image is displayed on the display screen. If the user's selection of a disease name is detected for the first time after the display of the display screen, a page of an electronic medical book containing differential items corresponding to the selected disease name is displayed on the display screen.