How unique is the Asymptotic Normalisation Coefficient (ANC) method?

The asymptotic normalisation coefficients (ANC) for the vertex ${}^{10}$B $\to$ ${}^9$Be + p is deduced from a set of different proton transfer reactions at different energies. This set should ensure the peripheral character of the reaction and availability of data for the elastic channels. The problems associated with the characteristics of the data and the analysis are discussed. For a subgroup of the set of available data, the uniqueness property of the extracted ANC is fulfilled. However, more measurements are needed before a definite conclusion can be drawn.