Citta Vithi in Abhidhamma There is a chapter under citta vithi in Abhidhammattha Sangaha. In which of the seven books in Abhidhamma this concept appear?
As you mentioned, Chapter IV of the Sangaha describes citta vithi. The Visuddhimagga includes many partial references (look under "cognitive series" in the index) but no complete analysis. Clearly, the material in the Sangaha is a later development of what is found in the Visuddhimagga (perhaps 500 years earlier). The material in the Visuddhimagga is a later development of sporadic references found in the Patthana (Conditional Relations). For example, on page 72 of PTS Conditional Relations Vol II, it says, "advertance (avajjana) is related to five-fold consciousness through proximity condition". On page 74, it says, "Life-continuum (bhavanga) without applied thought but with sustained thought is related to advertance by proximity condition." Proximity condition (and contiguity condition) imply a process. In summary, the fully-worked-out version found in the Sangaha was developed from fragments found in the Visuddhimagga (and commentaries) and these were developed from even earlier (and much more primitive) fragments found in the Patthana.