Sakai´s claims in Sino-Japanese war

[GuerraCivil]

I wonder if someone knows the dates and locations of Sakai´s claims in China below and if they were confirmed:

Claim on 3.10.1939: DB 3 - if I remember correctly Sakai did not claim this bomber as destroyed, only damaged. Some sources attribute Sakai with a "destroyed" DB 3. But this is not the case. According to Chinese/Soviet records no DB 3´s were lost on 3.10.1939. Case closed?

Claim on spring or summer of 1941: the first kill with Zero: Chinese biplane, unidentified type (I-15 bis, I-153 or a trainer?). This happened in connection with an strafing attack against Chinese airfield. I tried to find info on this from Håkans Aviation Page, but could not find confirmation.

I have found the following claims from the book "Samurai", which has been much criticized and shown to unreliable in many parts (containing dubious material of Martin Caidin without the approval of Sakai). The book "Winged Samurai" has been recommended instead, but it is hard to find. I also doubt if it contains precise information on Sakai´s claims in Sino-Japanese war.