1. D. Grumiller, M. Leston, and D. Vassilevich, Phys. Rev., D89, No. 4, 044001 (2014).
2. D. Grumiller, J. Salzer, and D. Vassilevich, J. High Energy Phys., No. 12, 15 (2015).
3. J. Maldacena, D. Stanford, and Z. Yang [arXiv:1606.01857[hep-th]] (2016).
4. K. Jensen [arXiv:1605.06098[hep-th]] (2016).
5. J. Engelsöy, T. G. Mertens, and H. Verlinde, J. High Energy Phys., No. 07, 139 (2016).