1. A computer-implemented method of outputting multiple data sources, comprising: receiving a first user command to collect a plurality of data sources for outputting; collecting the plurality of data sources for outputting in accordance with the first user command; receiving a second user command to specify a print order for a plurality of pages of the data sources; displaying the plurality of data sources as a plurality of sheet representations that represent the plurality of pages, each of the sheet representations is overlayed with a number that represents a page order of the sheet representations that are selected to print according to the second user command, more than one of the sheet representations of the plurality of sheet representations are overlayed with the same number, thereby resulting in more than one of the data sources being selected to print on a given page; receiving a third user command to save or print the plurality of pages; and outputting the plurality of sheet representations according to the third user command.