Full protection and security, or similar
Indirect expropriation
Other
https://globalarbitrationreview.com/article/bulgaria-faces-new-ect-claims (requires subscription)
https://www.iareporter.com/articles/bulgaria-faces-new-intra-eu-ect-arbitration-as-children-of-former-yukos-associate-make-good-on-earlier-threat-to-bring-icsid-claim/ (requires subscription)
https://www.iareporter.com/articles/children-of-former-yukos-associate-put-bulgaria-on-notice-of-ect-dispute/ (requires subscription)