Kuipers-Zandberg, H., and R. Kircher. “THE OBJECTIVE AND SUBJECTIVE ETHNOLINGUISTIC VITALITY OF WEST FRISIAN: PROMOTION AND PERCEPTION OF A MINORITY LANGUAGE IN THE NETHERLANDS”. Sustainable Multilingualism / Darnioji Daugiakalbystė, no. 17, Mar. 2023, pp. 1-25, doi:10.2478/sm-2020-0011.