| MinByTSource, TKey(IEnumerableTSource, FuncTSource, TKey) | 
            Returns the minimal elements of the given sequence, based on
            the given projection.
             Obsolete.  | 
| MinByTSource, TKey(IEnumerableTSource, FuncTSource, TKey, IComparerTKey) | 
            Returns the minimal elements of the given sequence, based on
            the given projection and the specified comparer for projected values.
             Obsolete.  |