Acid etching as surface treatment method for luting of glass ceramic restorations, part 1: acids, application protocol and etching effectivness - Bajraktarova Valjakova E, Grozdanov A, Guguvcevski Lj, Korunoska Stevkova V, Kapusevska B, Gigovski, Mijoska A, Bajraktarova Misevska C (Open Access Macedonian Journal of medical Sciences,2018; 6 (3) : 568-573, 2018)