*Definition [#ybe87b03]
-Let (X, T , E) be a [[soft space>soft topological space]] over X. A [[soft set]] (F , E) over X is said to be a soft closed set in X, if its [[relative complement(soft)]] (F , E)′ belongs to T .

*Definition [#u9eeed96]
-Shabir Muhammad, Naz Munazza, ''On soft topological spaces.'' (English summary), Comput. Math. Appl. 61 (2011), no. 7, 1786-1799.