Robert Coons is the author of Internal Elixer cultivation. He takes a seemingly straightforward approach to dantain cultivation with sitting meditational practice. I recently noticed he has a youtube channel as well. One thing I can say I like about his work is that it is simple and straightforward. I enjoyed reading his book
I read his book quite some time ago so I don't remeber his exact lineage but I know he and his master have strong ties to white cloud temple in Beijing.