1. Sulistiyani dan Rosidah Ambar T.. 2017, Manajemen Sumber Daya Manusia, Yogyakarta: Graha Ilmu
2. Badan Pusat Statistik Indonesia, 2020
3. Badan Pusat Statistik Kota Sibolga, 2023. Kota Sibolga Dalam Angka, Sibolga: BPS Sibolga
4. Creswell J. W., & Poth C. N. 2018. Qualitative Inquiry and Research Design Choosing Among Five Approaches (4th Edition ed.). California: Sage Publishing.
5. Sunyoto Danang. 2015. Strategi Pemasaran. Yogyakarta : Center for Academic Publishing Service (CAPS)