1. IRENA International Renewable Energy Agency, Global Energy Transformation: A Roadmap to 2050, 2018. www.irena.org.
2. International Energy Agency (IEA), Summary: Energy Technology Perspectives 2017, OECD/IEA, 2017. www.iea.org.
3. FCH JU, Hydrogen Roadmap Europe: A Sustainable Pathway for the European Energy Transition, 2019.
4. Hydrogen Europe’s Strategic Plan 2020–2030, Hydrogen: enabling a zero emission Europe, 2018.
5. R.B. GmbH, Fuel Cell Electric Buses – Potential for Sustainable Public, Transport in Europe, 2015.