2-Naphthalenecarboxylic acid,4-(2-(4-chloro-3-sulfophenyl)diazenyl)-3-hydroxy-,strontium salt (1:1); 2-Naphthalenecarboxylic acid,4-((4-chloro-3-sulfophenyl)azo)-3-hydroxy-,strontium salt (1:1); Strontium 4-((4-chloro-3-sulphonatophenyl)azo)-3-hydroxy-2-n