Let

$G$ be an additive Abelian group of order

$v$. A

$(v,k,\lambda )$- difference set in

$G$ is the set

$D$ of

$k$ elements of

$G$ such that any non-zero element

$g\in G$ has

$\lambda $ representations in the form

$g={d}_{1}-{d}_{2}$, where

${d}_{1}$,

${d}_{2}$ are two elements of

$D$. The existence of

$(v,k,\lambda )$-difference sets in non-cyclic Abelian groups was yet studied for

$k\le 50$ by E. S. Lander. This paper continues this investigation for

$k\le 100$. Five criteria of non-existence of a difference set are used. The results are listed in a table. In this table still some unsolved cases (denoted by the symbol?) remain.