I found these works in physical form from a Road Map called. "Road Map of Malaya" issued by Shell in 1951. According to Copyright Act 1987 (Malaysia Act 332)

From my copy of the Copyright Act (332) 1987:

• • 23. Duration of copyright in works of Government, Government organizations and international bodies.**

Copyright which subsists in works of the Government, Government organizations and international bodies under this Act shall continue to subsist until the expiry of a period of fifty years computed from the beginning of the calendar year next following the year in which the work was first published.

Hence Its passed copyright. The copyright is issued by the Surveyor General of the Federation of Malaya in 1951. Which has now expired.

Is it listed under Survey Department Federation of Malaya No.88-1951