context source (HKRMS)
HKBWS. (2013). Hong Kong Bird Report 2011. <em>The Hong Kong Bird Watching Society.</em> [details]
context source (Schelde)
Maris, T.; Beauchard, O.; Van Damme, S.; Van den Bergh, E.; Wijnhoven, S.; Meire, P. (2013). Referentiematrices en Ecotoopoppervlaktes Annex bij de Evaluatiemethodiek Schelde-estuarium Studie naar “Ecotoopoppervlaktes en intactness index”. <em>Monitor Taskforce Publication Series, 2013-01. NIOZ: Yerseke.</em> 35 pp. (look up in IMIS) [details]
basis of record
BODC. (2009). Species list from the British Oceanographic Data Centre. <em>BODC. (2009). Species list from the British Oceanographic Data Centre.</em> [details]
additional source
Liu, J.Y. [Ruiyu] (ed.). (2008). Checklist of marine biota of China seas. <em>China Science Press.</em> 1267 pp. (look up in IMIS) [details] Available for editors 
ecology source
BirdLife International. (2018). Anser anser. <em>The IUCN Red List of Threatened Species 2018.</em> e.T22679889A131907747., available online at https://doi.org/10.2305/iucn.uk.2018-2.rlts.t22679889a131907747.en [details]
From editor or global species database
Present