Creating 4th, 5th.... dependent list (validation List)

I found this site that explains creating the third dependent list
http://www.contextures.com/xlDataVal02.html
by using this formula =INDIRECT(SUBSTITUTE(B2&C2," ",""))
I understand how it works but my list has more than 3 columns.
Should I use =INDIRECT(SUBSTITUTE(B2&C2&D2," ","")) ---for the fourth column? and B2&C2&D2&E2 for the 5th column? (...and so on)

thanks in adv