魏书
The (554) "Book of Wei" records that both the Northern Wei emperors Daowu (r. 386–409) and Mingyuan (r. 409–423) often took Cold-Food Powder, and "In the end, they were 'unable to handle state affairs' and eventually died of elixir poisoning." Wagner noted that the Northern Wei "barbarian" rulers regarded the drug as a "status symbol."