APA

(2003). The GLOBALLY harmonized system of classification and labelling of chemicals : The purple book volume 1 & II. New York: United Nation.

Chicago

2003. The GLOBALLY harmonized system of classification and labelling of chemicals : The purple book volume 1 & II. New York: United Nation.

Harvard

(2003). The GLOBALLY harmonized system of classification and labelling of chemicals : The purple book volume 1 & II. New York: United Nation.

MLA

The GLOBALLY harmonized system of classification and labelling of chemicals : The purple book volume 1 & II. New York: United Nation. 2003.