diff --git a/src/chapter09graphs/GraphAdjacencyMatrix.py b/src/chapter09graphs/GraphAdjacencyMatrix.py
index 5ac7a20..30e84e1 100644
--- a/src/chapter09graphs/GraphAdjacencyMatrix.py
+++ b/src/chapter09graphs/GraphAdjacencyMatrix.py
@@ -15,7 +15,7 @@ def __init__(self, node):
         self.visited = False  
 
     def addNeighbor(self, neighbor, G):
-	G.addEdge(self.id, neighbor)
+        G.addEdge(self.id, neighbor)
 
     def getConnections(self, G):
         return G.adjMatrix[self.id]
@@ -36,49 +36,50 @@ class Graph:
     def __init__(self, numVertices, cost=0):
         self.adjMatrix = [[-1] * numVertices for _ in range(numVertices)]
         self.numVertices = numVertices
-	self.vertices = []
-	for i in range(0, numVertices):
-		newVertex = Vertex(i)
-		self.vertices.append(newVertex)
+        self.vertices = []
+        for i in range(0, numVertices):
+            newVertex = Vertex(i)
+            self.vertices.append(newVertex)
 
     def setVertex(self, vtx, id):
-	if 0 <= vtx < self.numVertices:
-		self.vertices[vtx].setVertexID(id)
+        if 0 <= vtx < self.numVertices:
+            self.vertices[vtx].setVertexID(id)
 
     def getVertex(self, n):
         for vertxin in range(0, self.numVertices):
-		if n == self.vertices[vertxin].getVertexID():
-			return vertxin       
-        return -1
+            if n == self.vertices[vertxin].getVertexID():
+                return vertxin
+        else:
+            return -1
 
     def addEdge(self, frm, to, cost=0): 
         if self.getVertex(frm) != -1 and self.getVertex(to) != -1:
-		self.adjMatrix[self.getVertex(frm)][self.getVertex(to)] = cost
-		# For directed graph do not add this
-		self.adjMatrix[self.getVertex(to)][self.getVertex(frm)] = cost  
+            self.adjMatrix[self.getVertex(frm)][self.getVertex(to)] = cost
+            # For directed graph do not add this
+            self.adjMatrix[self.getVertex(to)][self.getVertex(frm)] = cost  
 		
     def getVertices(self):
-	vertices = []
+        vertices = []
         for vertxin in range(0, self.numVertices):
-		vertices.append(self.vertices[vertxin].getVertexID())
+            vertices.append(self.vertices[vertxin].getVertexID())
         return vertices
 	
     def printMatrix(self):
-	for u in range(0, self.numVertices):
-		row = []
-		for v in range(0, self.numVertices):
-			row.append(self.adjMatrix[u][v])
-		print row	
+          for u in range(0, self.numVertices):
+                   row = []
+                   for v in range(0, self.numVertices):
+                             row.append(self.adjMatrix[u][v])
+                   print (row)	
 	
     def getEdges(self):
         edges = []
-	for v in range(0, self.numVertices):
-		for u in range(0, self.numVertices):
-			if self.adjMatrix[u][v] != -1:
-				vid = self.vertices[v].getVertexID()
-				wid = self.vertices[u].getVertexID()
-				edges.append((vid, wid, self.adjMatrix[u][v]))
-	return edges
+        for v in range(0, self.numVertices):
+                  for u in range(0, self.numVertices):
+                           if self.adjMatrix[u][v] != -1:
+                                     vid = self.vertices[v].getVertexID()
+                                     wid = self.vertices[u].getVertexID()
+                                     edges.append((vid, wid, self.adjMatrix[u][v]))
+        return edges
     
 if __name__ == '__main__':
     G = Graph(5)
@@ -87,12 +88,12 @@ def getEdges(self):
     G.setVertex(2, 'c')
     G.setVertex(3, 'd')
     G.setVertex(4, 'e')
-    print 'Graph data:'  
+    print ('Graph data:')  
     G.addEdge('a', 'e', 10)  
     G.addEdge('a', 'c', 20)
     G.addEdge('c', 'b', 30)
     G.addEdge('b', 'e', 40)
     G.addEdge('e', 'd', 50)
     G.addEdge('f', 'e', 60)
-    print G.printMatrix()      
-    print G.getEdges()    
+    print (G.printMatrix())      
+    print (G.getEdges())