diff --git a/lib/Element.ts b/lib/Element.ts
index d380bfc..160c16c 100644
--- a/lib/Element.ts
+++ b/lib/Element.ts
@@ -13,6 +13,9 @@ export class Element {
   }
 
   public constructor (name: string, parent = '') {
+    const regex = /^[a-z_][a-z_0-9]+$/iu;
+    if (!regex.test (name))
+      throw new Error ('invalid name specified');
     this.name = name;
     this.parent_name = parent;
   }
diff --git a/lib/Graph.ts b/lib/Graph.ts
index 399441f..6582c77 100644
--- a/lib/Graph.ts
+++ b/lib/Graph.ts
@@ -1,9 +1,16 @@
 import { Element } from './Element';
 import { Edge } from './Edge';
 import { Node } from './Node';
-import { GraphStyles } from './Styles';
+import { GraphStyles, NodeStyles } from './Styles';
 import { Color } from './Color';
 
+interface NodeOptions {
+  name: string;
+  label: string;
+  style: NodeStyles;
+  color: Color;
+}
+
 export class Graph extends Element {
   public children: Array<Graph> = [];
   public nodes: Array<Node> = [];
@@ -13,7 +20,7 @@ export class Graph extends Element {
   public color?: Color;
 
   // eslint-disable-next-line @typescript-eslint/naming-convention
-  public toString (level = 0): string {
+  public toString (): string {
     const header = this.parent
       ? `subgraph cluster_${this.full_name}`
       : `digraph ${this.full_name}`;
@@ -23,54 +30,61 @@ export class Graph extends Element {
     if (this.style)
       attributes.push ({ name: 'style', value: this.style.toString () });
 
-    let attrs = `\n  ${attributes.map ((v) => `${v.name} = ${v.value}`)
-      .join ('\n  ')}\n`;
-    let children = `\n  ${this.children.map ((c) => c.toString (level + 1))
-      .join ('\n  ')}\n`;
-    let nodes = `\n  ${this.nodes.map ((c) => c.toString ())
-      .join ('\n  ')}\n`;
-    let edges = `\n  ${this.edges.map ((c) => c.toString ())
-      .join ('\n  ')}\n`;
+    let attrs = `\n${attributes.map ((v) => `${v.name} = ${v.value}`)
+      .join ('\n')}\n`;
+    let children = `\n${this.children.map ((c) => c.toString ())
+      .join ('\n')}\n`;
+    let nodes = `\n${this.nodes.map ((c) => c.toString ())
+      .join ('\n')}\n`;
+    let edges = `\n${this.edges.map ((c) => c.toString ())
+      .join ('\n')}\n`;
 
-    if (attrs === '\n  \n')
+    if (attrs === '\n\n')
       attrs = '';
-    if (children === '\n  \n')
+    if (children === '\n\n')
       children = '';
-    if (nodes === '\n  \n')
+    if (nodes === '\n\n')
       nodes = '';
-    if (edges === '\n  \n')
+    if (edges === '\n\n')
       edges = '';
 
-    return `${header} {${attrs}${children}${nodes}${edges}}`
-      .replace (/\n/gu, `\n${'  '.repeat (level)}`)
+    const indented = `${attrs}${children}${nodes}${edges}`
+      .replace (/\n$/u, '')
+      .replace (/^/gmu, '  ')
+      .split ('\n')
+      .map ((v) => v.trimRight ())
+      .join ('\n');
+
+    return `${header} {${indented}\n}`
       .replace (/^\s+$/gmu, '');
   }
 
-  public add_node (constructor: ((g: Node) => void) | string): string {
-    if (typeof constructor === 'string') {
-      this.nodes.push (new Node (constructor, this.full_name, constructor));
-      return this.nodes[this.nodes.length - 1].full_name;
-    }
+  public add_node (constructor: ((n: Node) => void) | string): string {
     const node = new Node ('unnamed', this.full_name);
-    constructor (node);
+
+    if (typeof constructor === 'string') {
+      node.name = constructor;
+      node.label = constructor;
+    }
+    else { constructor (node); }
+
     this.nodes.push (node);
     return node.full_name;
   }
 
   public add_graph (constructor: ((g: Graph) => void) | string): string {
-    if (typeof constructor === 'string') {
-      this.children.push (new Graph (constructor, this.full_name));
-      return this.children[this.children.length - 1].full_name;
-    }
     const graph = new Graph ('unnamed', this.full_name);
-    constructor (graph);
+
+    if (typeof constructor === 'string')
+      graph.name = constructor;
+    else
+      constructor (graph);
+
     this.children.push (graph);
     return graph.full_name;
   }
 
   public add_edge (origin: string, target: string): void {
-    this.edges.push (
-      new Edge (`${this.full_name}_${origin}`, `${this.full_name}_${target}`)
-    );
+    this.edges.push (new Edge (origin, target));
   }
 }
diff --git a/lib/Node.ts b/lib/Node.ts
index b04e136..815712e 100644
--- a/lib/Node.ts
+++ b/lib/Node.ts
@@ -9,7 +9,7 @@ export class Node extends Element {
   public style?: NodeStyles;
   public color?: Color;
 
-  public constructor (name: string, parent?: string, label?: string) {
+  public constructor (name: string, parent: string, label?: string) {
     super (name, parent);
     this.label = label;
   }
@@ -28,19 +28,36 @@ export class Node extends Element {
   // eslint-disable-next-line @typescript-eslint/naming-convention
   public toString (): string {
     const attributes = [];
+    if (this.label || this.is_table) {
+      attributes.push ({
+        name:  'label',
+        value: this.is_table
+          ? this.serialized_table
+          : this.label
+      });
+    }
     if (this.style)
       attributes.push ({ name: 'style', value: this.style.toString () });
     if (this.color)
       attributes.push ({ name: 'color', value: this.color.toString () });
 
-    const attrs = attributes.map ((v) => `${v.name}="${v.value}"`)
-      .join (',');
+    const attrs = attributes.map ((v) => {
+      const d = (/\n/u).test (v.value as string)
+        ? [
+          '<',
+          '>'
+        ]
+        : [
+          '"',
+          '"'
+        ];
+      return `${v.name}=${d[0]}${v.value}${d[1]}`;
+    })
+      .join (', ');
+
+    if (attributes.length > 0)
+      return `${this.full_name} [${attrs}]`;
 
-    if (this.is_table || typeof this.label !== 'undefined') {
-      return `${this.full_name} [label=<${this.is_table
-        ? this.serialized_table
-        : this.label}>${attributes.length > 0 ? `,${attrs}` : ''}]`;
-    }
     return `${this.full_name}`;
   }
 }
diff --git a/test/Graph.ts b/test/Graph.ts
index 1e5466a..e591755 100644
--- a/test/Graph.ts
+++ b/test/Graph.ts
@@ -1,16 +1,27 @@
 import test from 'ava';
-import { Graph, GraphStyles, Color } from '../lib';
+import { Graph, GraphStyles, Color, NodeStyles } from '../lib';
 
 const result = `digraph foo {
   subgraph cluster_foo_baz {
     color = #ff0000
     style = bold
 
-    foo_baz_asd [label=<asd>]
+    subgraph cluster_foo_baz_nested {
+      color = #808080
+      style = dotted
+
+      subgraph cluster_foo_baz_nested_unnamed {
+        color = #808080
+        style = dotted
+      }
+    }
+
+    foo_baz_asd [label="asd"]
+    foo_baz_test [style="bold", color="#808080"]
   }
 
-  foo_baz [label=<baz>]
-  foo_foo [label=<foo>]
+  foo_baz [label="baz"]
+  foo_foo [label="foo"]
 
   foo_foo -> foo_baz
 }`;
@@ -22,13 +33,31 @@ test ('serialize', (t) => {
   g.add_graph ((graph) => {
     graph.name = 'baz';
     graph.add_node ('asd');
+    graph.add_node ((n) => {
+      n.name = 'test';
+      n.style = NodeStyles.bold;
+      n.color = Color.gray;
+    });
+
+    // eslint-disable-next-line no-shadow
+    graph.add_graph ((g) => {
+      g.style = GraphStyles.dotted;
+      g.color = Color.gray;
+      g.name = 'nested';
+
+      // eslint-disable-next-line no-shadow, max-nested-callbacks
+      g.add_graph ((g) => {
+        g.style = GraphStyles.dotted;
+        g.color = Color.gray;
+      });
+    });
     graph.style = GraphStyles.bold;
     graph.color = Color.red;
   });
 
-  g.add_node ('baz');
-  g.add_node ('foo');
-  g.add_edge ('foo', 'baz');
+  const baz = g.add_node ('baz');
+  const foo = g.add_node ('foo');
+  g.add_edge (foo, baz);
 
   const serialized = g.toString ();
 
diff --git a/test/Node.ts b/test/Node.ts
index e897fca..829cace 100644
--- a/test/Node.ts
+++ b/test/Node.ts
@@ -2,12 +2,12 @@ import test from 'ava';
 import { NodeStyles, Node, Color } from '../lib';
 
 const serialized_simple
-= 'bar_foo [label=<baz>,style="dashed",color="#00ff00"]';
+= 'bar_foo [label="baz", style="dashed", color="#00ff00"]';
 const serialized_table = `bar_foo [label=<<table>
   <tr><td>foo</td><td>bar</td><td>baz</td></tr>
   <tr><td>bar</td><td>baz</td><td>foo</td></tr>
   <tr><td>baz</td><td>foo</td><td>bar</td></tr>
-</table>>,style="invis",color="#00ff00"]`;
+</table>>, style="invis", color="#00ff00"]`;
 
 test ('serialize simple', (t) => {
   const g = new Node ('foo', 'bar', 'baz');
@@ -47,3 +47,10 @@ test ('serialize table', (t) => {
   t.is (g.full_name, 'bar_foo');
   t.is (serialized, serialized_table);
 });
+
+test ('adhere to naming convention', (t) => {
+  t.throws (() => {
+    const n = new Node ('invalid.name', 'parent');
+    return n.toString ();
+  }, { message: 'invalid name specified' });
+});