Nurminski, E.A.
(1979).
On ε-Subgradient Methods of Non-Differentiable Optimization.
In:
International Symposium on Systems Optimization and Analysis.
pp. 187-195 Germany: Springer Berlin Heidelberg.
ISBN 978-3-662-39921-7 10.1007/978-3-662-39921-7_18.