Lomashishiksha 2.3

2.3

kareṇuṃ tsahayorvidyātkurviṇīṃ ṛddhikarayoḥ
hariṇīṃ dṛśayorvidyād hāritāṃ ṛśakārayoḥ

One should know Kareṇu in [the combination of] t and s, Kurviṇī in ṛ and dh or k;
one should know Hariṇī in d and ṛ or ś, and Hāritā in ṛ and ś;