@Misc{Wiki,
 howpublished = {\url{https://en.wikipedia.org/wiki/Gymnocephalus_cernuus}}
} 

@Book{Kooy2010,
 author = {Kooijman, S.A.L.M.},
 year = {2010},
 title  = {Dynamic Energy Budget theory for metabolic organisation},
 publisher = {Cambridge Univ. Press, Cambridge},
 pages = {Table 4.2 (page 150), 8.1 (page 300)},
 howpublished = {\url{../../../bib/Kooy2010.html}}
} 

@Techreport{Emme2004,
 author = {W. A. M. van Emmerik},
 year = {2004},
 title = {Kennisdocument pos, \emph{Gymnocephalus cernuus} ({L}innaeus, 1758)},
 institution = {Sportvisserij Nederland},
 series = {Kennisdocument},
 volume = {5},
 howpublished = {\verb+\url{http://www.sportvisserijnederland.nl/files/kennisdocument-snoekbaars_4560.pdf}+}
}