You cant import a sheet from a paret file but you can export a sheet to a part file, that is why you need to open the part with the views that you need and export the sheet from that file to your working file.
Open your part withthe views that you would like to export. File>Export>Part
choose existing, select the part you would like to export the sheets to. select "drawing selection" and choose the sheets that have your views that you would like to export.