Erratum to: analyzing student interactions and meaning construction in computer bulletin board discussions

PCT No. PCT/FI97/00332 Sec. 371 Date Nov. 24, 1998 Sec. 102(e) Date Nov. 24, 1998 PCT Filed May 30, 1997 PCT Pub. No. WO97/45396 PCT Pub. Date Dec. 4, 1997The invention relates to N-bis- or N-tris-[(1,2-dicarboxy-ethoxy)-ethyl]-amine derivatives having the formula (I) and R2 is hydrogen, an alkali metal or an earth-alkali metal. The invention also relates to a method for preparing the same and their use as chelating agents.