Ekbert "One-Eyed" Count in the Ambergau, Graf im Ambergau und Derlingau Vogt des Bistums Münster - Sources?

What are the Sources for this profile? According to Medlands, Bia and an Unknownhusband had one son, Friedrich:

BIA [Pia] (-25 May -) A list of names in the Libri Confraternitatum Sancti Galli sets out (in order) "Thieterich, Reginhilt, *, Oto, Amalrat, Perectheid, Friderun, Pia", immediately after a list of family members of Heinrich I King of Germany and his wife, which no doubt refers to the latter's parents and sisters[54]. "Otto…rex" granted property "in Gereslevo…in pago Svevia in comitatu Crhistiani" on the request of "Friderici fidelis nostri" to "nobili matronæ…Biæ ipsius…matri" by charter dated 21 Oct 937, in consultation with "Burchardi, Ebarhardi, Chuonradi, Heinrici atque Utonis…comitum"[55], although it is not known whether this was the same Bia.

The necrology of Merseburg records the death "25 May" of "Bia soror regine Mahtildis"[56]. same person as…? BIA (-after 21 Oct 937). "Otto…rex" granted property "in Gereslevo…in pago Svevia in comitatu Crhistani" to "nobili matronæ Bia ipsius…matri" at the request of "Friderici fidelis nostri" by charter dated 21 Oct 937[57].

It is not certain that this refers to the same person as Bia, daughter of Theoderic, but this is likely to be the case. No other noble lady of this name has been identified around the date of this charter, and "matrona" is the term usually applied to members of the high nobility. The wording of the charter suggests that Bia's husband had died before the date of the grant.

m --- (-before 21 Oct 937). The name of Bia's husband is not known.

Bia & her husband had one child:

1. Friedrich (d. after 21 October 937)

http://fmg.ac/Projects/MedLands/SAXONY.htm#Mathildedied968