102 PIR-sensor-on-Wikipedia
http://txplo.re/2eeg9yQ

102 Learn-about-Absolute-Zero
http://txplo.re/2fRhjAf

102 HC-SR501-datasheet
http://txplo.re/2dJSPHK

104 Sketch1-on-Github
http://txplo.re/2dwenu0

104 Sketch2-on-Github
http://txplo.re/2ecz7YM

105 Sketch1-on-Github
http://txplo.re/2dwenu0

106 Sketch-2-on-Github
http://txplo.re/2ecz7YM