Observation of B→ ϕK and B→ ϕK*

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We have studied two-body charmless hadronic decays of B mesons into the final states phi K and phi K*. Using 9.7 million BB pairs collected with the CLEO II detector, we observe the decays B- -> phi K- and B0 -> phi K*0 with the following branching fractions: BR(B- -> phi K-)=(5.5 +2.1-1.8 +- 0.6) x 10⁻⁶ and BR(B0 -> phi K*0)=(11.5 +4.5-3.7 +1.8-1.7) x 10⁻⁶. We also see evidence for the decays B0 -> phi K0 and B- -> phi K*-. However, since the statistical significance is not overwhelming for these modes we determine upper limits of <12.3 x 10⁻⁶ and <22.5 x 10⁻⁶ (90% C.L.) respectively.