http://fmjd.org/?p=titles
1976 H. Wiersma Netherlands Amsterdam, Netherlands Tournament
1979 H. Wiersma Netherlands Utrecht, Netherlands match with A. Gantwarg
1981 H. Wiersma Netherlands Different locations, Netherlands match with A. Gantwarg (2+, 18=, 0-)
1983 H. Wiersma Netherlands Heerenveen, Netherlands match with J. van der Wal (1+, 19=, 0-)
1983 H. Wiersma Netherlands Amsterdam, Netherlands Tournament (Compromise resolution between KNDB, SUDF and FMJD of april 1984, ratified by GA 1984.)
1984 H. Wiersma Netherlands Moscow/Rotterdam, USSR/Netherlands match with V. Virni (1+, 18=, 1-)