A system, method, apparatus and computer program product for providing location based functions and mobile e-commerce comprising a central processing unit including a processor, a storage device, and programming stored in the storage device, a display device, an audio input device, an audio output device, a communications module, a commerce module, an image module, and a location module. A process for producing an electron source having an electron emitting portion at one end of a rod, which comprises a step of forming the electron emitting portion by machining, and a step of removing a damaged layer at the surface of the formed electron emitting portion by chemical polishing or electrolytic polishing. The articles are initially fed into one group of pockets only. The ring-like structure is tailored to slip onto and engage a finger in various positions and remain attached to the finger when the finger is flicked. This mechanism is essential for regulating the mass and structural integrity of bone. Further, links are memorized in a form of link list, and the position of the link in the link list is not changed in the course of addingdeleting a link, thereby enabling a direct reference to each of the links in the link list by the position of the link.