1. International Monetary Fund - Report for Selected Countries and Subjects. (n.d.). Retrieved February 25 2020 from https://www.imf.org/external/pubs/ft/weo/2018/01/weodata/weorept.aspx?pr.x=52&pr.y=11&sy=1980&ey=2023&scsm=1&ssd=1&sort=country&ds=.&br=1&c=532&s=NGDP_RPCH PPPGDP PPPPC PCPIPCH LUR GGXWDG_NGDP&grp=0&a= International Monetary Fund - Report for Selected Countries and Subjects. (n.d.). Retrieved February 25 2020 from https://www.imf.org/external/pubs/ft/weo/2018/01/weodata/weorept.aspx?pr.x=52&pr.y=11&sy=1980&ey=2023&scsm=1&ssd=1&sort=country&ds=.&br=1&c=532&s=NGDP_RPCH PPPGDP PPPPC PCPIPCH LUR GGXWDG_NGDP&grp=0&a=
2. Gross Domestic Product (GDP) by major economic. (n.d.). Retrieved February 9 2020 from https://www.censtatd.gov.hk/hkstat/sub/sp250.jsp? tableID =036&ID=0&productType=8 Gross Domestic Product (GDP) by major economic. (n.d.). Retrieved February 9 2020 from https://www.censtatd.gov.hk/hkstat/sub/sp250.jsp? tableID =036&ID=0&productType=8
3. The development process of the UN/CEFACT modeling methodology
4. The Buy -Ship-Pay Reference Models. (n.d.). Retrieved May 2020 from http://tfig.unece.org/contents/buy-ship-pay-model.htm The Buy -Ship-Pay Reference Models. (n.d.). Retrieved May 2020 from http://tfig.unece.org/contents/buy-ship-pay-model.htm