1. [1] Etkin, D.S. 2010. Worldwide analysis of in-port vessel operational lubricant discharges and leaks
2. [2] Ahlbohm, J & Duus, U. 2007. Clean Shipping Project, Gothenburg
3. [3] Etkin, op. cit, calculates that 4.6 million to 28.6 million litres of the estimated total are lost through the sterntube.
4. [4] IMO MSC/Circ.1056 MEPC/Circ.399 23 December 2002, clause 7.2.3
5. [5] DNV Rules for Classification of Ships; Newbuildings; Special Equipment and Systems; Additional Class. January 2011 Part 6, Chapter 12: Section 2 — page 17 (clause C 1000) and Section 3-page 23 (clause C 1100), as modified 1st January 2013