  This article is devoted to inverse problems of recovering point sources in
mathematical models of heat and mass transfer. The main attention is paid to
well-posedness questions of these inverse problems with pointwise
overdetermination conditions. We present conditions for existence and
uniqueness of solutions to the problem, display non-uniqueness examples, and,
in model situations, we give estimates on the number of measurements that allow
completely identify sources and their locations. The results rely on asymptotic
representations of Green functions of the corresponding elliptic problems with
a parameter. They can be used in constructing new numerical algorithms for
determining a solution.
