https://www.iareporter.com/articles/chinese-owned-renewable-energy-investor-lodges-intra-eu-ect-claim-against-bulgaria/ (requires subscription)
https://globalarbitrationreview.com/article/bulgaria-faces-new-ect-claims (requires subscription)
https://www.iareporter.com/articles/renewable-energy-arbitration-against-bulgaria-is-discontinued/ (requires subscription)