Questions regarding invited parents to US

I have green card, plan to invite parents for visiting. I want to know what documents I need to prepare and what they need to prepare. Please list the documents as "Required" and "Not Required But Preferred" if you can.

Thanks for the help

所有跟帖： 

• 從其他論壇轉貼，供參考:xmm11 於 於文學城我愛我家 -TX_Kitty- ♀ (11598 bytes) () 03/07/2007 postreply 07:52:32

• xmm11 於文學城我愛我家 (2) -TX_Kitty- ♀ (2870 bytes) () 03/07/2007 postreply 07:53:27

• Thanks a lot -LazyBoy- ♀ (0 bytes) () 03/07/2007 postreply 08:07:18