Vidagdha Madhava - By Rupa Gosvami / Audio

https://www.google.com/search?q=Vidagdha+Madhava

http://ia600502.us.archive.org/18/items/TFIC_ASI_Books/VidagdhaMadhavaOfSriRupadevaGosvami.pdf

Giving Gopala Diety to Vallab's Son

http://aitanya.blogspot.com/search/label/Vallabahcharya

Top Five limbs of devotional service

CC Madhya 22.128: "

1. One should associate with devotees,
2. chant the holy name of the Lord, 
3. hear Śrīmad-Bhāgavatam, 
4. reside at Mathurā 
5. worship the Deity with faith and veneration.

CC Madhya 22.129: "These five limbs of devotional service are the best of all. Even a slight performance of these five awakens love for Kṛṣṇa.

Source 

https://www.google.com/search?q=CC+Madhya

Patal Devi

Opposite to Nand Bhavan, there is an underground cave where Sanatana Goswami lived during his stay at Gokul. The cave is about 30 feet deep. It is in this cave, that Sanatana Goswami found the deity of Yogmaya Devi in the form of goddess Durga. He named the deity as Patal Devi as it was found underground. Santana Goswami worshipped that deity of Goddess Durga for many years. Later on the cave was enlarged and the temple was built at the place commemorating the deity of Patal Devi. Now the entrance of the cave has been blocked and apart from the smaller deity, a larger deity of Goddess Durga has also been established nearby.