Chemicool
Chemicool: Manganese
Chemicool.com offers a very well organized set of data tables describing the chemical and physical properties of manganese. Very helpful.
Chemicool
Chemicool: Neptunium
This Chemicool site offers excellent data tables with known information on Neptunium.
Chemicool
Chemicool: Cesium
Chemicool.com offers a very good summary of the key physical and chemical properties of cesium. Well organized.