1. Submission of Japan's nationally determined contribution (NDC), https://www.env.go.jp/press/files/jp/113675.pdf.
2. Technology roadmap: hydrogen and fuel cells,2015
3. European Commission – The European green deal, https://ec.europa.eu/info/sites/info/files/european-green-deal-communication_en.pdf.
4. Hydrogen, the bridge between Africa and Europe;Wijk,2020
5. Hydrogen and related issues, basic hydrogen strategy,2017