Found the following hamletworks.org entries referring to line 688
View Commentary Note for 684
684
Ham. I will.
1.5.2
View Commentary Note for 688
688
Ham. Alas poore Ghost.
1.5.4
View Immaterial Textual Note for 688
688
Ham. Alas poore Ghost.
1.5.4
View Material Textual Note for 688
688
Ham. Alas poore Ghost.
1.5.4