1. Asknature. Retrieved August 2019 from https://asknature.org/
2. Asknature. Retrieved January 2020, from https://asknature.org/strategy/elevated-leaves-reduce-evaporation/
3. Asknature. Retrieved January 2020, from https://asknature.org/?s=Pebble+Plants#.XlWPvnduIq0
4. Asknature. Retrieved January 2020, from https://asknature.org/strategy/pressure-makes-air-move/
5. Asknature. Retrieved January 2020, from https://asknature.org/?s=Selaginella%20Ferns&page=0&is_v=1