Information:  - Thai Airways International Public Company Limited, trading as THAI is the flag carrier airline of Thailand. Formed in 1988, the airline has its corporate headquarters in Vibhavadi Rangsit Road, Chatuchak District, Bangkok, and primarily operates out of Suvarnabhumi Airport. THAI is a founding member of the Star Alliance. The airline is the largest shareholder of the low-cost carrier Nok Air with a 39 percent stake, and it launched a regional carrier under the name Thai Smile in the middle of 2012 using new Airbus A320 aircraft.  - Don Mueang International Airport (, or colloquially as ) (or also [old] Bangkok International Airport) is one of two international airports serving Greater Bangkok, the other one being Suvarnabhumi Airport (BKK).  - Nok Air (, derived from "nok" (), the Thai word for "bird") is a low-cost airline in Thailand operating mostly domestic services out of Bangkok's Don Mueang International Airport. Thai Airways owns the largest stake in the airline.  - Siam General Aviation Company Limited ( Thai :      ) was an airline in Thailand . Previously operated as an arm for Nok Air under the brand Nok Mini , the company ended their partnership in March 2014 , with Nok Air . SGA were in talks to be acquired by Thai Air Asia but this fell through and the airline is no longer operating .    What entity does 'sga airlines' has the relation 'airline hub' with?
The answer to this question is:
don mueang international airport