No gift, sale, assignment or transfer of any saving fund bank book bearing evidence of bank deposits or of any interest in the deposits represented thereby, shall be valid unless the same shall be in writing and the same or a copy thereof delivered to the bank issuing such bank deposit book.
Wis. Stat. § 241.25
Transfer of bank book to be in writing
Official source: Wisconsin State Legislature. Reproduced from public-domain Wisconsin statutes; confirm against the official source for the current text. Not legal advice.