1. "Arctic Studies Center - Resources - Frequently Asked Questions", Naturalhistory.si.edu, 2017. Online. Available: https://naturalhistory.si.edu/arctic/html/resources_faq.html.
2. Brechner, M.; Both, A.J. Hydroponic Lettuce Handbook. Cornell Controlled Environment Agriculture; Cornell University. Available online: http://www.cornellcea.com/attachments/CornellCEALettuceHandbook.pdf.
3. Growth Technology, What is Hydroponic growing?, Available Online: http://www.growthtechnology.com/growtorial/what-is-hydroponic-growing/.
4. Simply Hydroponics and Organics, Getting Started with Hydroponics, Available Online: http://www.simplyhydro.com/getstart.htm.
5. LEAF, Tech Specs, Available Online: https://www.getleaf.co/.