Back to the Abstract

	1 Introduction
	2 The samples
	3 The optical classification criteria
	4 X-ray spectral analysis
	5 Optical obscuration versus X-ray absorption
	6 X-ray bright optically normal galaxies (XBONG)
	7 Type II QSO candidates
	8 Summary and conclusions
	References
	Online Material
	Appendix A: Illustrating figures about selection effects in our sample

	List of tables
	List of figures