RT Journal Article SR Electronic(1) A1 Abraham, O. A1 Cötel, Ph. A1 Leonard, Ch. A1 Piwakowski, B. A1 Shahrour, I.YR 1998 T1 Application of the "impact echo method" to the detection of underground cavities part II: field experiments JF , VO OP SP cp-43-00092 DO https://doi.org/10.3997/2214-4609.201407117 PB European Association of Geoscientists & Engineers, SN 2214-4609, AB , UL https://www.earthdoc.org/content/papers/10.3997/2214-4609.201407117