As the economy slowly improves and fewer failed banks offer acquisition opportunities, Springfield-based Great Southern Bank has turned to a tried-and-true growth strategy to enter new markets in Oklahoma and Texas. Great Southern Bancorp Inc. (Nasdaq: GSBC) is expanding its commercial lending footprint this month with offices in Tulsa, Okla., and Dallas, marking the bank's first entry into Oklahoma and Texas. The moves mirror a loan production office expansion model of the early to mid-2000s that took the bank into new markets – Kansas City, St. Louis and Fayetteville, Ark. – and turned into retail opportunities. "That's three markets where we have a pretty good retail presence, but our initial entry was through LPOs," Great Southern President and CEO Joe Turner said. More recently, Great Southern has grown through acquisitions. The company purchased four failed banks between 2009 and 2012, growing its footprint to roughly 100 branches from nearly 50.