Drammen records 1850 to 1900

Please suggest sources of birth/family records for Drammen Norway for the period 1850 to 1900. Have identified at least three siblings born in Drammen but only have Americanized names. Thora Lee - born 1886 John Lee - born 1890 Carl Lee - born ? Their father was a sea captain and one sibling son was lost at sea. Origninal name of Johansen but with all variations of this name I cannot find any leads in Digitalarkivet All Ellis Island immigration records show Thora Lee and John Lee. I apologize for the weak information but I am just starting my genealogy search and am very inexperienced. Thank you for any help. Norm Lee