1. 1. HELCOM recommendation 11/10 Guidelines for capacity calculation of sewage system on board passenger ships (1990) Baltic Marine Environment Protection Commission.
2. 2. HELCOM overview on port reception facilities for sewage in the Baltic Sea area and related trends in passenger traffic (2013) Baltic Marine Environment Protection Commission.
3. 3. Annex IV of MARPOL 73/78 convention. HELCOM: Interim guidance on technical and operational aspects of delivery of sewage by passenger ships to port reception facilities (2013) Baltic Marine Environment Protection Commission.
4. 4. Chin-Shan, Lu; Wen-Hong, Liu; Wooldridge Ch. (2014) Maritime environmental governance and green shipping. Maritime Policy & Management 41(2): 131–133.
5. 5. Demand study port infrastructure (2013) Project CLEANSHIP report. (Clean Baltic Sea Shipping, funded by Baltic Sea Programme 2007-2013).