Brahma Samhita

 

https://www.google.com/search?q=Goloka+Brahma+Samhita

Mahatmya

 https://www.google.com/search?q=Vasudeva+Mahatmya

Sixteen

After bowing down to the door keepers viz 

1. Virabhanu, 
2. Chandrabhanu 
3. Surbyabhanu,  
4. Vasubhanu, 
5. Devabhanu, 
6. Shakrabhanu, 
7. Ratnabhanu, 
8. Suparshva, 
9. Vishala, 
10. Vrishabha and others, 
11. Amshu, 
12. Bala, 
13. Subala, 
14. Devaprastha, 
15. Varuthapa, and 
16. Sridama, 

Sage Narada entered into the palace of Krishna after obtaining their permission. 

https://www.google.com/search?q=16+doors+of+goloka

Billion

 https://www.google.com/search?q=billion+gopas+gopis

Million

Ananta to Goloka

1. https://www.google.com/search?q=five+hundred+million+yojanas
2. https://www.google.com/search?q=five+hundred+million+yojanas+above+Vaikuntha

Ashram / Cottages

1. https://www.google.com/search?q=five+hundred+million+asramas
2. https://www.google.com/search?q=with+many+yuthika+flowers+with+five+hundred+million+forest+cottages

Gopis / Gopas

1. https://www.google.com/search?q=five+hundred+million+gopis
2. https://www.google.com/search?q=five+hundred+million+gopas

Vani

 https://www.google.com/search?q=Goloka+Vani