Energy level diagram, Lanthanoid, Rare earth, Monoclinic

• Er-La-O-V-Yb
• Er-O-Si-Tm-Y-Yb
• Er-O-W-Y
• Al-Eu-O-Sr
• Er-O-W-Y-Yb
• lanthanoid
• rare earth
• chalcogen
• luminescent
• transitional