Are you seeking info related to doing lab work on milk, for a presentation to health workers assisting mothers, for a leaflet for parents? There is a hige amount of material available and the most suitable depends on the purpose and the audience.
Yamawaki N, Yamada M, Kan-no T, Kojima T, Kaneko T, Yonekubo A.: Macronutrient, mineral and trace element composition of breast milk from Japanese women.
J Trace Elem Med Biol. 2005; 19(2-3): 171-81. Epub 2005 Oct 24. https://www.ncbi.nlm.nih.gov/pubmed/16325533 https://www.researchgate.net/publication/7442815
Parr, R. M., DeMaeyer, E. M., Iyengar, V. G., Byrne, A. R., Kirkbright, G. F., Sch?ch, G., Niinist?, L., Pineda, O., Vis, H. L. Hofvander, Y. and Omololu, A.: Minor and Trace Elements in Human Milk from Guatemala, Hungary, Nigeria, Philippines, Sweden and Zaire - Results from a WHO/IAEA Joint Project.
Biological Trace Element Research 29 (1): 51-75. Apr. 1991