Syntheses and structures of ammonium transition-metal dialuminium tris(phosphate) dihydrates (NH<sub>4</sub>)<i>M</i>Al<sub>4</sub>(PO<sub>4</sub>)<sub>3</sub>·2H<sub>2</sub>O (<i>M</i> = Mn and Ni)
Acta crystallographica. Section E, Crystallographic communications