The claim that certain languages mark first- or second-person personal pronouns for gender is a well-known linguistic fact (found in languages such as Arabic, Hebrew, and Japanese, where speech-act participant pronouns vary depending on the social or grammatical gender of the speaker or addressee). No citation is needed for this elementary linguistic observation.
The claim states that some languages have first- or second-person personal pronouns marked for gender. This is a basic, uncontroversial linguistic fact about human language (e.g., Arabic distinguishes masculine and feminine forms in second- and third-person, and sometimes first-person in certain dialects/contexts; Japanese first- and second-person pronouns often encode speaker/hearer gender or social register). Because this is a matter of everyday observation and textbook linguistic typology, it falls under COMMON_KNOWLEDGE, requiring no citations.