Lucia, grevinna av Gleichen

[M.Sjöstrom]

There appears to have been a lady Lucia, wife of Henry, count of Gleichen (himself flourished 1275-1300). The said Henry seems to have resided in Sweden quite a lot (his close relatives were mostly Danish).
 
I have found a reference in ÄSF, according to which Lucia's gener was the infamous Svantepolk Knutsson. And I have drawn a conclusion that presumably Lucia was a blood relative, perhaps a cousin, of Svantepolk's wife Benedikte Sunadotter who was from the Bjellbo earl dynasty.
 
Is there any more references to Lucia, in any German, Swedish, Danish or whatever primary sources?
 
How probable is that Lucia was a Swede? Was her husband Henry a lot elsewhere than in Sweden, or is his presence in Sweden such that very probably his marriage was Swedish? how big a portion of his life?
 
Any indications that Lucia instead would have been German, or Danish?
 
And, what are main primary sources of Middle Ages families and their marriages and identities of wives, in Germany? In Gleichen?