select Doc.DocNum, GR.GR, GR_Seq = GR.Seq, GE.GE, GE_Seq = GE.Seq, Ref.Ref, Ref_Seq = Ref.Seq

from Doc

cross join ( values (1),(2),(3),(4),(5),(6),(7),(8),(9) ) N (n)

left outer join GR on GR.DocNum = Doc.DocNum and N.n = GR.Seq

left outer join GE on GE.DocNum = DOC.DocNum and N.n = GE.Seq

left outer join Ref on Ref.DocNum = DOC.DocNum and N.n = Ref.Seq

where Ref.Ref is not null

order by Doc.DocNum, N.n