Tourist visa for Beijing

Hi
Here you say:
3. For applicants who apply for tourist and family visit visa, they should also provide following documents:
a. Invitation letter from a Chinese organization or a permanent resident in PRC; or
b. Air ticket booking record (round trip) and hotel reservation.
I want to go to Beijing for a month. In order to apply for the visa, is it ok if I provide them with only the air tickets? I am going to stay with a friend during that month, do I need to have an invitation letter from that friend, or is my friends' address enough?

Really need your help, this bureaucracy is a pain
Thank you