Charak Samhita
सहितौ स्वादुलवणौ तद्वत् कट्वादिभिः पृथक्। युक्तौ शेषैः पृथग्योगं यातः स्वादूषणौ तथा ॥१९॥
Now, dropping the sweet taste, the group of two of sour and salt combining consecutively with pungent, sour and astringent tastes forms with the addition respectively of bitter, astringent and pungent tastes, three separate groups of ‘four tastes’. (1) sour-salt-pungent-bitter (2) sour-salt-bitter-astringent (3) sour-salt-astringent-pungent.
english translation
sahitau svAdulavaNau tadvat kaTvAdibhiH pRthak। yuktau zeSaiH pRthagyogaM yAtaH svAdUSaNau tathA ॥19॥
hk transliteration by Sanscript