1. "Google project tango " https://get.google.com/tango/. "Google project tango " https://get.google.com/tango/.
2. "Google cardboard " https://vr.google.com/cardboard/. "Google cardboard " https://vr.google.com/cardboard/.
3. "Google daydream " https://vr.google.com/daydream/. "Google daydream " https://vr.google.com/daydream/.
4. "Samsung gear vr " http://www.samsung.com/global/galaxy/gear-vr/. "Samsung gear vr " http://www.samsung.com/global/galaxy/gear-vr/.