Secret names of the four worlds

[Stella_de_Assiah]

Does anybody know where I can find information on the secret names on the four qabalistic worlds?

qabalistic world/secret name:
atziluth - aub
briah - seg
yetzirah - mah
assiah - ben

I am trying to find out why those worlds have secret names, why those specific names, their significance and use.

Thank you.