ASEAN Arctic Zone of the Russian Federation Black Sea Blue Economy (BE) sectors COVID-19 pandemic China CiteSpace Danube River Polar Silk Road R language RCEP Ukraine VOSviewer bibliometric analysis bic Book Industry Communication::G Reference, information & interdisciplinary subjects::GP Research & information: general bic Book Industry Communication::K Economics, finance, business & management::KC Economics::KCN Environmental economics bic Book Industry Communication::T Technology, engineering, agriculture::TQ Environmental science, engineering & technology::TQK Pollution control blue economy blue economy (BE) coastal areas and municipalities coastal regions coastal tourism comparative advantage connectivity demographic structure distance learning economic growth educational institutions employers fish