diff --git a/plesna/graph.py b/plesna/graph.py
index 00b8aff..4e04baa 100644
--- a/plesna/graph.py
+++ b/plesna/graph.py
@@ -1,3 +1,4 @@
+from functools import reduce
 from typing import Callable
 
 from pydantic import BaseModel
@@ -23,11 +24,54 @@ class Graph:
         self._edges = []
         self._nodes = set()
 
-    def append(self, edge: Edge):
+    def add_edge(self, edge: Edge):
         self._edges.append(edge)
         self._nodes.add(edge.source)
         self._nodes.add(edge.target)
 
+    def add_node(self, node: Node):
+        self._nodes.add(node)
+
     @property
     def nodes(self):
         return self._nodes
+
+    def get_edges_from(self, node: Node) -> list[Edge]:
+        """Get all edges which have the node as source"""
+        return [edge for edge in self._edges if edge.source == node]
+
+    def get_edges_to(self, node: Node) -> list[Edge]:
+        """Get all edges which have the node as target"""
+        return [edge for edge in self._edges if edge.target == node]
+
+    def get_direct_targets_from(self, node: Node) -> set[Node]:
+        """Get direct nodes that are accessible from the node"""
+        return set(edge.target for edge in self._edges if edge.source == node)
+
+    def get_targets_from(self, node: Node) -> set[Node]:
+        """Get all nodes that are accessible from the node
+
+        If the graph have a loop, the procedure be in an infinite loop!
+
+        """
+        direct_targets = self.get_direct_targets_from(node)
+        undirect_targets = [self.get_targets_from(n) for n in direct_targets]
+        undirect_targets = reduce(lambda x, y: x.union(y), undirect_targets, set())
+
+        return direct_targets.union(undirect_targets)
+
+    def get_direct_sources_from(self, node: Node) -> set[Node]:
+        """Get direct nodes that are targeted the node"""
+        return set(edge.source for edge in self._edges if edge.target == node)
+
+    def get_sources_from(self, node: Node) -> set[Node]:
+        """Get all nodes that are targeted the node"""
+        direct_sources = self.get_direct_sources_from(node)
+        undirect_sources = [self.get_sources_from(n) for n in direct_sources]
+        undirect_sources = reduce(lambda x, y: x.union(y), undirect_sources, set())
+
+        return direct_sources.union(undirect_sources)
+
+    def is_valid_dag(self):
+        for node in self._nodes:
+            pass
diff --git a/tests/graphs/test_graph.py b/tests/graphs/test_graph.py
index 1fbe18b..9729ac9 100644
--- a/tests/graphs/test_graph.py
+++ b/tests/graphs/test_graph.py
@@ -1,7 +1,20 @@
+import pytest
+
 from plesna.graph import Edge, Graph, Node
 
 
-def test_init():
+def test_append_nodess():
+    nodeA = Node(name="A")
+    nodeB = Node(name="B")
+
+    graph = Graph()
+    graph.add_node(nodeA)
+    graph.add_node(nodeB)
+
+    assert graph.nodes == {nodeA, nodeB}
+
+
+def test_append_edges():
     nodeA = Node(name="A")
     nodeB = Node(name="B")
     nodeC = Node(name="C")
@@ -10,7 +23,69 @@ def test_init():
     edge2 = Edge(arrow_name="arrow", source=nodeB, target=nodeC)
 
     graph = Graph()
-    graph.append(edge1)
-    graph.append(edge2)
+    graph.add_edge(edge1)
+    graph.add_edge(edge2)
 
     assert graph.nodes == {nodeA, nodeB, nodeC}
+
+
+def test_init_edges_nodes():
+    nodeA = Node(name="A")
+    nodeB = Node(name="B")
+    nodeC = Node(name="C")
+
+    edge1 = Edge(arrow_name="arrow", source=nodeB, target=nodeC)
+
+    graph = Graph()
+    graph.add_node(nodeA)
+    graph.add_edge(edge1)
+
+    assert graph.nodes == {nodeA, nodeB, nodeC}
+
+
+@pytest.fixture
+def nodes():
+    return {
+        "A": Node(name="A"),
+        "B": Node(name="B"),
+        "C": Node(name="C"),
+        "D": Node(name="D"),
+    }
+
+
+@pytest.fixture
+def edges(nodes):
+    return {
+        "1": Edge(arrow_name="arrow", source=nodes["A"], target=nodes["C"]),
+        "2": Edge(arrow_name="arrow", source=nodes["B"], target=nodes["C"]),
+        "3": Edge(arrow_name="arrow", source=nodes["C"], target=nodes["D"]),
+    }
+
+
+@pytest.fixture
+def graph(nodes, edges):
+
+    graph = Graph()
+    graph.add_edge(edges["1"])
+    graph.add_edge(edges["2"])
+    graph.add_edge(edges["3"])
+    return graph
+
+
+def test_get_edges_from(nodes, edges, graph):
+    assert graph.get_edges_from(nodes["A"]) == [edges["1"]]
+
+
+def test_get_targets_from(nodes, edges, graph):
+    assert graph.get_direct_targets_from(nodes["A"]) == set([nodes["C"]])
+    assert graph.get_direct_targets_from(nodes["C"]) == set([nodes["D"]])
+    assert graph.get_direct_targets_from(nodes["D"]) == set()
+    assert graph.get_targets_from(nodes["A"]) == set([nodes["C"], nodes["D"]])
+
+
+def test_get_sources_from(nodes, edges, graph):
+    assert graph.get_direct_sources_from(nodes["A"]) == set()
+    assert graph.get_direct_sources_from(nodes["C"]) == set([nodes["A"], nodes["B"]])
+    assert graph.get_direct_sources_from(nodes["D"]) == set([nodes["C"]])
+
+    assert graph.get_sources_from(nodes["D"]) == set([nodes["A"], nodes["B"], nodes["C"]])