dsf to dwg conversion is typically searched by users that own old Micrografx Designer files (.dsf) and wonder how to open or access these drawings using modern software, or even directly export it to a different format, in this case DWG.
The successor of Micrografx Designer can be found as part of CorelDRAW Technical Suite actually, and it should be still possible to import .dsf file to Corel Designer.
Another possibility for users without access to Corel software, is to download Micrografx Designer from abandonware websites like WinWorld library and export the files to some exchange format that can be imported to modern software.