@misc{ wiki:DTMF,
   author = "Wikipedia",
   title = "Dual-tone multi-frequency signaling",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling",
   note = "[Online; accessed 27-August-2016]"
 }

@misc{ wiki:Goertzel,
   author = "Wikipedia",
   title = "Goertzel algorithm",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Goertzel_algorithm",
   note = "[Online; accessed 27-August-2016]"
 }

@misc{ wiki:FIR,
   author = "Wikipedia",
   title = "Finite impulse response",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Finite_impulse_response",
   note = "[Online; accessed 27-August-2016]"
 }

@misc{ wiki:IIR,
   author = "Wikipedia",
   title = "Infinite impulse response",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Infinite_impulse_response",
   note = "[Online; accessed 27-August-2016]"
 }

@misc{ wiki:Nyquist-Shannon,
   author = "Wikipedia",
   title = "Nyquist–Shannon sampling theorem",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem",
   note = "[Online; accessed 27-August-2016]"
 }

@misc{ wiki:Z-transform,
   author = "Wikipedia",
   title = "Z-transform",
   year = "2016",
   url = "https://en.wikipedia.org/wiki/Z-transform",
   note = "[Online; accessed 27-August-2016]"
 }

@article{ DTMF_genave,
   author = "Genave.com",
   title = "DTMF Explained",
   url = "http://www.genave.com/dtmf.htm",
   note = "[Online; accessed 27-August-2016]"
}