Patent (2018) - Rienk Eelkema (inventor), R. Eelkema (inventor), A. G. Denkova (inventor), AG Denkova (inventor), A.G. Denkova (inventor), Antonia Denkova (inventor), Antonia G. Denkova (inventor), Antonia G. Denkova (inventor), A. C. Laan (inventor), Adrianus C. Laan (inventor), A.C. Laan (inventor), A.D. Weller (inventor)