Doubt with 'OracleDataReader' is defined in an assembly that is not referenced

I'm using the Oracle.ManagedDataAccess.Client, it is referenced to the project containing the context.

I have my Context:

namespace Generico.Repositorio
{
    public class Contexto : IDisposable
    {
        private readonly OracleConnection minhaConexao;

        public Contexto()
        {
            minhaConexao = new OracleConnection(ConfigurationManager.ConnectionStrings["Conexao"].ConnectionString);
            minhaConexao.Open();
        }

        public void ExecutaComando(string strQuery)
        {
            var cmdComando = new OracleCommand
            {
                CommandText = strQuery,
                CommandType = CommandType.Text,
                Connection = minhaConexao
            };

            cmdComando.ExecuteNonQuery();
        }

        public OracleDataReader ExecutaComandoComRetorno(string strQuery)
        {
            var cmdComando = new OracleCommand(strQuery, minhaConexao);
            return cmdComando.ExecuteReader();
        }

        public void Dispose()
        {
            if (minhaConexao.State == ConnectionState.Open)
                minhaConexao.Close();
        }
    }
}

In the application I have an error: "The 'OracleDataReader' type is defined in an assembly that is not referenced. You should add a reference to the assembly 'Oracle.ManagedDataAcces'

namespace Generico.Aplicacao
{
    public class AtualizaAplicacao
    {
        private Contexto contexto;

        public string Consulta(string codigo)
        {
            int retorno = 0;
            var strQuery = "";

            //apensas vamos retornar o pais, não vamos gravar ou atualizar
            strQuery = string.Format("select * from pais WHERE codigo = '{0}' ", codigo);

            using (contexto = new Contexto())
            {//erro em contexto.ExecutaComandoComRetorno
                var reader = contexto.ExecutaComandoComRetorno(strQuery);
                while (reader.Read())
                {
                    //pega o Id da cidade
                    retorno = Convert.ToInt32(reader["codigo"]);
                }
                reader.Close();
            }

            return retorno.ToString();
        }




    }
}