doi:10.1186/s40623-015-0228-9 - include Author, year
Russell, 1971 - include DOI
http://cdpp.cnes.fr/00428.pdf - This link is broken. I suggest asking authors to post to DOI minting service such as Zenodo or putting the doc in the repository (if copyright allows).
I have suggestions for links and references
doi:10.1186/s40623-015-0228-9 - include Author, year
Russell, 1971 - include DOI
http://cdpp.cnes.fr/00428.pdf - This link is broken. I suggest asking authors to post to DOI minting service such as Zenodo or putting the doc in the repository (if copyright allows).
http://nssdc.gsfc.nasa.gov/space/helios/coor_des.html - This link is broken. Same suggestions as 3.
Hapgood, 1992.