Geodesic
Extremal problems in a subclass of entire functions of finite power
Matematičeskie zametki, Tome 19 (1976) no. 1, pp. 19-28 
S. A. Kas'yanyuk. Extremal problems in a subclass of entire functions of finite power. Matematičeskie zametki, Tome 19 (1976) no. 1, pp. 19-28. http://geodesic.mathdoc.fr/item/MZM_1976_19_1_a2/
@article{MZM_1976_19_1_a2,
     author = {S. A. Kas'yanyuk},
     title = {Extremal problems in a~subclass of entire functions of finite power},
     journal = {Matemati\v{c}eskie zametki},
     pages = {19--28},
     year = {1976},
     volume = {19},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_19_1_a2/}
}
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Voir la notice de l'article provenant de la source Math-Net.Ru

We study the subclass $W_\sigma(A)$ of the class of entire transcendental functions $f(z)$of exponential type with index not greater than sgr satisfying the condition $$ \int_{-\infty}^\infty|f(x)|^2\,dx\le A^2 $$ We find the set of values of the quantities $f(z)$, $f'(z)$, etc. when $z$ is fixed and $f(z)$ runs through the subclass $W_\sigma(A)$. We study extremal values of functionals of the type $\Phi(f(z),f'(z))$. In particular, we obtain upper bounds on the quantities $|f(z+\beta/2)\pm f(z-\beta/2)|$ и $|af'(z)+b\sigma f(z)|$.