Hey guys, apologies if its posted already. I am a self employed online music teacher and my students are mostly from different countries. Can they send me the reference letter without a letter head? the reference letters will be sent to me as a PDF or scanned copy of the original document they wrote.can i submit those as proof? does the reference letter need attestation from a lawyer from their country? Kindly help as im about to apply under self employed program (not EE).