J. N. Singh Yadav (2001). Yadavas of South India. Yadava Publications Original from the University of Michigan. पपृ॰ 6–8.The term Abhira, Gopa, Gopala, Gwala,Ghosa, Ghosi, Gvalia,Gvali, etc. are the professional appellations from those Yadavas who tended cows in pastoral age and adopted agriculture later on.
Akhtar Majeed, Jamia Hamdard (नई दिल्ली, India). Centre for Federal Studies (2000). Coalition politics and power sharing. Manak Publications Pvt. Ltd., Original from the University of Michigan. पृ॰ 52. आई॰ऍस॰बी॰ऍन॰9788186562963.सीएस1 रखरखाव: एक से अधिक नाम: authors list (link)