also known as GraviGUTs

“Nature is a unity. This pen is made of atoms and it falls in the earth's gravitational field. Hence there must be one framework, one law of nature of which these two theories are different aspects. It would be absurd if there were two irreconcilable laws of physics, one for one domain of the world and another for another domain. Even in 1915 Einstein was aware of the issue, and in his very first paper about gravitational waves, he mentions the paradox of how to fit relativity together with the quantum.” https://www.edge.org/conversation/lee_smolin-loop-quantum-gravity-lee-smolin

• GraviGUTs

• On Unification of Gravity and Gauge Interactions by Ali H. Chamseddine, Viatcheslav Mukhanov (2016). They consider the group $SO(1,13)$ and use the $SO(10)$ part as a conventional GUT. They get problems with mirror fermions. To unify all families they propose the usage of the group $SO(1,21)$.)
• Graviweak Unification by F. Nesti, R. Percacci

• On the History of Unified Field Theories by Hubert F. M. Goenner