Complex sentence: The form "Glomma" is used in Østfold and Akershus counties, while in Hedmark and Sør-Trøndelag counties the river is called (and written) "Glåma".
Split into simpler sentences: The form "Glomma" is used in the counties of Østfold and Akershus. In the counties of Hedmark and Sør-Trøndelag the river is called (and written) "Glåma".