Lusiantoro, Luluk, and Wakhid Slamet Ciptono. 2012. “An Alternative to Optimize the Indonesian’s Airport Network Design: An Application of Minimum Spanning Tree (MST) Technique”. Gadjah Mada International Journal of Business 14 (3), 267-302. https://jurnal.ugm.ac.id/v3/gamaijb/article/view/15372.