coupon collector problem

Hi: all:

I am reading the paper" Practical Network Support for IP Traceback" ,
in this paper , there is one sentence related to the " coupon collector
problem", however I am new with that topic. Just paste the sentence
here, what I want to ask, what is expension of d(ln(d)+o(1)) , how can
draw the conclusion.

Thanks
"
Finally,as per the well-known coupon collector problem, the number
of trials required to select one of each of d equi-probable items
is d(ln(d) + O(1))."
Received on Sat Dec 3 04:20:25 2005