Mass. Gen. Laws ch. 6, § 39B

Each state agency shall furnish the state library 1 copy of its publications, provided in the format in which it was created, such as print or electronic, not later than 5 working days after creation of said publication. The state library shall make copies available for public consultation and for permanent historic preservation. Digitized publications shall be made available to the Library of Congress and to each of the state's regional public libraries through the state library's digital collections.