- Souček V.
- The minimum existence of functional $\intop \nolimits _{a}^{b}F(x(t),y(t),\mathaccent "705F x(t),\mathaccent "705F y(t))\mskip \thinmuskip dt$. 11:2 (1970), pp. 205 -- 225.
- Wajch E.
- Compactifications and $L$-separation. 29:3 (1988), pp. 477 -- 484.