Thomas Engel:
Quantum Chemistry & Spectroscopy
First Edition
Pearson/Benjamin Cummings, 2006
ISBN 0-8053-3843-8
2D MO-Diagram for 2,6,6aλ4-Trithiapentalene.
J. Spanget-Larsen, Chen E., I. Shim: J. Am. Chem. Soc. 116, 11433 (1994)