A digital music display stand includes an operating unit containing processing structure, memory and a display. The marker may be a line symbol, a protrusion, a pit, etc. The method further includes receiving a second prompt to reveal the hidden content of the e-book and temporarily revealing the hidden content, in response to the second prompt, while presenting the non-selected content of the e-book. A control circuit is connected at least to a respective first semiconductor switching element and the voltage boosting circuit. In summary, the present method subjects a suitably N-protected dione to difluoramination followed by protolytic N-deprotection by addition of a superacid and subsequent nitration utilizing an electrophilic nitrating agent to yield the diazocinium salt.