Benko, M., Gfrerer, H., Outrata, J. Calculus for Directional Limiting Normal Cones and Subdifferentials. Set-Valued and Variational Analysis. 2019, 27(3), 713-745. ISSN 1877-0533. E-ISSN 1877-0541. Dostupné z: http://library.utia.cas.cz/separaty/2018/MTR/outrata-0493120.pdf https://link.springer.com/article/10.1007%2Fs11228-018-0492-5