We present magnetic resonance measurements on the S = 1/2 spin ladder
systems (VO)(2)P2O7 (two legs), on the cuprates SrCu2O3 (two legs) and
Sr2Cu3O5 (three legs). The measurements were performed in the frequen
cy range 35-400 GHz at temperatures down to 1.5 K and in magnetic fiel
ds up to 14 T.