Linked from
The 6 pages that link to Iron(II) sulfate, each with the reason it gives.
MordantBroader topic: Iron salts can darken natural dyes and shift their hues.
Iron(II)Broader topic: It is a common soluble compound that supplies Fe²⁺ ions.
Iron(III) sulfateCompared with: It contains iron(II), unlike the iron(III) in this compound.
Iron(II) chlorideCompared with: It is a common alternative source of Fe²⁺ in aqueous chemistry.
Ammonium iron(II) sulfateRelated: It supplies the iron(II) component of the double salt.