Helen L. Hein and Joachim Schwarte, Products in Early Development Phases: Ecological Classification and Evaluation Using an Interval Arithmetic Based Calculation Approach. journal = {International Journal of Energy and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology. April 2019, vol. 149(5). 368 - 374 [viewed 20 September 2024]. Available from: https://publications.waset.org/pdf/10010386.