Xian Railway Station to Huashan

Take a regular tourist bus from the east square of Xi'an Railway Station to the Jade Spring Temple at the foot of the Huashan Mountain. It operates between 06:30 and 19:00. The one-way ticket costs CNY 39.5 and round-trip ticket costs CNY 66.5. A single trip takes 1.5 hours or so.
Question: How do i know which one is the 'regular tourist bus'? Any bus#?