We consider the Dirichlet problems for second order linear elliptic equations in non-divergence and divergence forms on a bounded domain $ \Omega $ in $ \mathbb{R}^n $, $ n \ge 2 $: \begin{document}$ -\sum\limits_{i, j = 1}^n a^{ij}D_{ij} u + b \cdot D u + cu = f \;\;\text{ in }~~ \Omega \quad \text{and} \quad u = 0 \;\;\text{ on }~~ \partial \Omega $\end{document} and \begin{document}$ - {\rm div} \left( A D u \right) + \text{div}\, (ub) + cu = \text{div}\, F \;\;\text{ in }~~ \Omega \quad \text{and} \quad u = 0 \;\;\text{ on }~~ \partial \Omega , $\end{document} where $ A = [a^{ij}] $ is bounded, uniformly elliptic, and of vanishing mean oscillation (VMO). The main purpose of this paper is to study unique solvability for both problems with $ L^1 $-data. We prove that if $ \Omega $ is of class $ C^{1} $, $ \text{div}\, A + b\in L^{n, 1}( \Omega; \mathbb{R}^n) $, $ c\in L^{\frac{n}{2}, 1}( \Omega) \cap L^s( \Omega) $ for some $ 1<s<\frac{3}{2} $, and $ c\ge0 $ in $ \Omega $, then for each $ f\in L^1 (\Omega ) $, there exists a unique weak solution in $ W^{1, \frac{n}{n-1}, \infty}_0 ( \Omega) $ of the first problem. Moreover, under the additional condition that $ \Omega $ is of class $ C^{1, 1} $ and $ c\in L^{n, 1}( \Omega) $, we show that for each $ F \in L^1 ( \Omega ; \mathbb{R}^n ) $, the second problem has a unique very weak solution in $ L^{\frac{n}{n-1}, \infty}( \Omega) $.
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