  An observable on a quantum structure is any $\sigma$-homomorphism of quantum
structures from the Borel $\sigma$-algebra of the real line into the quantum
structure which is in our case a monotone $\sigma$-complete effect algebras
with the Riesz Decomposition Property. We show that every observable is a
smearing of a sharp observable which takes values from a Boolean
$\sigma$-subalgebra of the effect algebra, and we prove that for every element
of the effect algebra there is its spectral measure.
