The idea of rgan pa bzhi can be found, for example, in the Vimalaprabhā. The corresponding Sanskrit terms have been recorded in Negi’s Tibetan-Sanskrit dictionary (from the Vimalaprabhā):
1. ye shes kyis rgan pa = jñānavṛddha
2. dka’ thub kyis rgan pa = tapovṛddha
3. thos pas rgan pa = śrutavṛddha
4. nor gyis rgan pa = dhanavṛddha
An explanation can be found in Mi-pham’s Dus ’khor nang le’u’i ’grel pa (MS, vol. 21/zha, pp. 290.5–291.6).