Include Shimba 1984 reference.

Author: aseth1

OpenSim/Common/C3DFileAdapter.h

@@ -97,7 +97,10 @@ class OSIMCOMMON_API C3DFileAdapter : public FileAdapter {
         options for expressing the force-plate measurements either as the
         net force and moments expressed at the ForcePlateOrigin, the 
         CentereOfPressure, or the PointOfWrenceApplication (PWA) as defined by
-        Shimba 1984*/
+        Shimba 1984. 
+        Takeshi Shimba, An estimation of center of gravity from force platform
+        data, Journal of Biomechanics, 17(1), pp53-60, 1984.
+        */
     static
     Tables read(const std::string& fileName, 
                 ForceLocation wrt = ForceLocation::OriginOfForcePlate);