UNWTO Committee of Statistics (2021), Measuring the Sustainability of Tourism (MST): progress and way forward, p.12 http://tourismobservatory.ba.aegean.gr/wp-content/uploads/2021/04/UNSC_BackgroundDocumentMST.pdf
UNWTO, 2018, Linking the TSA and The SEEA: A technical note http://tourismobservatory.ba.aegean.gr/wp-content/uploads/2021/04/tsa_seea_tech.note_final.pdf