Linked from
The 8 pages that link to Carl Gustaf Mosander, each with the reason it gives.
YttriumRelated: His work showed that early yttria contained multiple distinct elemental components.
LanthanumRelated: He identified lanthanum in 1839 while investigating cerium compounds.
TerbiumRelated: Mosander identified terbium in 1843 while studying yttria from Ytterby.
ErbiumRelated: Mosander identified erbium-containing material while studying minerals from Ytterby.