What are five characteristics that scientists use to group dissimilar organisms into common groups?

Question

List references too please.

Thank you.

http://faculty.fmcc.suny.edu/mcdarby/Majors101Book/Chapter_02-A_Bit_of_History/02-Explaining-Life-Classification.htm

http://www.uoregon.edu/~sanjay/pubs/bigfive.pdf