411 REFERENCE · Wikibooks
OpenSCAD User Manual/Integration with other applications
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
FreeCAD
OpenSCAD Workbench allows both import and export of *.CSG files - http://www.freecadweb.org/wiki/index.php?title=OpenSCAD_Module
FreeCAD to openSCAD converter http://www.thingiverse.com/thing:1751345