Migration to netstandard2.0 - CS0246: 'ExportAttribute' could not be found

When I try to migrate to the<TargetFramework>netstandard2.0</TargetFramework>

I have errorerror CS0246: The type or namespace name 'ExportAttribute' could not be found (are you missing a using directive or an assembly reference?)

here

 [Export( typeof( IViewModelRepositoryFactory ) )]internal sealed class ViewModelRepositoryFactory : IViewModelRepositoryFactory{    private readonly IViewModelFactory[] _viewModelFactories;    [ImportingConstructor]    public ViewModelRepositoryFactory( [ImportMany] IViewModelFactory[] viewModelFactories )

How to fix it - looks like I need some nuget package ?

Inside what nuget I can found netstandard2.0 version for ExportAttribute ?