The management of said library shall be under a board of law library Trustees, consisting of five (5) members, to be chosen in the manner hereinafter provided, to-wit:
(a) In counties having two or more district judges, two district judges of the county, who shall be selected by the district judges of said county, in counties having only one district judge, such district judge and the associate district judge of the county.
(b) The district attorney for the district that includes the county in which the law library is located, or an assistant district attorney who is designated by the district attorney.
(c) Two members of the county bar association who shall be chosen by the members thereof. The present members of the board of law library trustees shall remain in office until the expiration of their terms of office.