Patonay Katalin;  Szalontai Helga;  Jánószky Mihály;  Lovas Miklós;  Pénzesné Kónya Erika;  Zámboriné Németh Éva:   Main phenolic constituents of Mentha longifolia (L.) L. samples from Northern Hungary - extractability, variability and contribution to some in vitro antioxidant properties of the plant : [abstract].