The goal of this article is to obtain observability estimates for non-homogeneous elliptic equations in the presence a potential, posed on smooth bounded domain Ω R2 and observed from non-empty open subset ω⊂Ω. More precisely, V∈L∞(Ω;R), our main result shows that, when Ω⊂R2 has finite number holes, constant operator −Δ+V, with H2(Ω)∩H01(Ω), form C exp (C‖V‖L∞(Ω)1/2 log 1/2(‖V‖L∞(Ω))) where pos...