1. P. A. Vityaz', V. M. Kaptsevich, and V. K. Sheleg, Porous Powder Materials and Products Made of Them [in Russian], Vyshéishaya Shkola, Minsk (1987).
2. G. A. Kostornov, Permeable Metallic Fiber Materials [in Russian], Tékhnika, Kiev (1983).
3. A. G. Kostornov, ?Quantitative criteria of the porous structure of permeable fibrous materials,? Poroshk. Metall., No. 4, 80?87 (1977).
4. V. P. Georgiev, R. P. Todorov, A. G. Kostornov, et al., ?Regularity of the structure of porous materials in thin layers,? Poroshk. Metall., No. 6, 69?71 (1987).
5. Yu. N. Kryuchkov, ?Coefficient of tortuosity of a porous medium partly saturated with wetting liquid in filtering of gas,? Poroshk. Metall., No. 2, 50?55 (191).