(Update August 2018)
© IBO, downloaded from http://www.ibchem.com/root_pdf/Chemistry_guide_2016.pdf
© IBO, downloaded from http://www.ibchem.com/root_pdf/data_booklet_2016.pdf
Downloaded from
http://www.freshney.org/index2.htm
© Vernier, downloaded from https://www.vernier.com