• https://www.psychologytoday.com/blog/prescriptions-life/201311/helping-you-find-your-life-purpose


• https://philosophynow.org/issues/59/What_Is_The_Meaning_Of_Life


• http://thepositivitysolution.com/whats-really-important/


• https://www.theguardian.com/science/2007/jun/06/spaceexploration.uknews


• http://123infinity.com