Two of the greatest rabbis of the Bavli Jewish community in recent centuries address the status of a new type of fruit that arrived from the Far East. Is it a kosher etrog?

The question is addressed in two responsa, one by R. Abdullah Somekh and one by his student, R. Yosef Hayyim, both of Baghdad.

Link to the responsum: https://www.hebrewbooks.org/pdfpager.aspx?req=32212&st=&pgnum=379