I need help with music book.?!

I need help with music book.?

I am creating an encyclopedia of great women in music of the 20thC from all over the world. I want to include composers, drummers, singers, anyone who really set the mold for other women. I am finding a lot of great women but now I am stuck on who to pick.
What do you think I should use as my criteria for who gets in and who doesn’t? How should I go about choosing them? What common trait do you think I should look for in these women? I need a theme, besides the fact that they are women, to base the choices on so the book works as a coherent whole.

i would like to help u very much with ur encyclopedia and my mail is ahmed.gy@gmail.com
i listen for music like an addict and all my answers for ur questions is based on my own opinion and knowledge:

as for the first question and in general when discussing music you should first state the genre. some genres like underground musis and lounge music include lots of singers who r not known , not famous so u can neglect these genres.

The best way to choose them is by genre again.
like saying the best singer of old bossanova is astrud and the best singer of modern bossanova and is marisa monte.

Using the work old, classical, modern, contemporary music all helps in segmenting genres and singers.

the common trait to look for is the added value by these women. like saying that shania twain gave a modern look to country music, or saying that cesaria evora devolped the morna music.

hope my answers are useful , for further assistance u can mail me .