1. Wasserman, A.Diels−Alder Reactions; Elsevier: New York, 1965.
2. Padwa, A.1,3-Dipolar Cycloaddition Chemistry; Wiley-Interscience: New York, 1984; Vols. 1−2.
3. Huisgen, R.1,3-Dipolar Cycloaddition Chemistry; Wiley: New York, 1984; Vol. 1.
4. Mechanism of 1,3-dipolar cycloadditions. Reply