Found the following hamletworks.org entries referring to line 3120

View Commentary Note for 3120
3120 Hamlet return'd, shall knowe you are come home, 31204.7.130

View Immaterial Textual Note for 3120
3120 Hamlet return'd, shall knowe you are come home, 31204.7.130

View Material Textual Note for 3120
3120 Hamlet return'd, shall knowe you are come home, 31204.7.130