Kemija - 2013./14. ljeto - 30.

${\mathrm{H}\mathrm{P}\mathrm{O}}_2\backslash mathrm\{HPO\}\_\{2\}$

${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_3\backslash mathrm\{H\}\_\{3\}\; \backslash mathrm\{PO\}\_\{3\}$

${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_2\backslash mathrm\{H\}\_\{3\}\; \backslash mathrm\{PO\}\_\{2\}$

${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_4\backslash mathrm\{H\}\_\{3\}\; \backslash mathrm\{PO\}\_\{4\}$