1. Barbosa GL, Almeida Gadelha FD, Kublik N, Proctor A, Reichelm L, Weissinger E, Wohlleb GM, Halden RU (2015) Comparison of land, water, and energy requirements of lettuce grown using hydroponic vs. Conventional agricultural methods. Int J Environ Res Public Health 12(6):6879–6891
2. Bavec M, Robačer M, Stajnko D, Vukmanić T, Bavec F (2014) Sustainability of vegetable production systems evaluated by ecological footprint, 4th ISOFAR Scientific Conference. ‘Building Organic Bridges’, at the Organic World Congress 2014, 13–15 Oct., Istanbul, Turkey
3. Bundschuh J, Tomaszewska B, Ghaffour N, Reardon-Smith K, Chen G, Mushtaq S, Hamawand I, Maraseni T, Banhazi T, Mahmoudi H, Goosen M, Diogenes L A (2017) Solar, wind and geothermal energy applications in agriculture: back to the future? Research Gate.com, chapter. 1, pg. 1–3, 5–10
4. Danish Agriculture & Food Council (2018) Available from:
https://agricultureandfood.dk
, (Access: 9 August, 2018)
5. Estrada A (2017) Utilization of natural light in indoor applications: simulation and implementation, Texas State University, chapter. 1, 2, pg. 2–3, 15–18