Influence of frequency of pulsed current during the plasma electrolytic oxidation on the corrosion resistance of coatings formed on magnesium alloy $AZ91$ / Anna KOŃKO, WOJCIECH GĘBAROWSKI, Piotr PALIMĄKA, Stanisław PIETRZYK // W: ICNFM 2015 : [2\textsuperscript{nd} International Conference on Non-Ferrous Metals] : Cracow, Poland, June 22–24 2015 : book of abstracts. — [Kraków : AGH], [2015]. — S. 93