1 | [1] "Alkaloids", Nature's Curse or Blessing By Manfred Hesse. Verlag Helvetica Chimica Acta, Zürich, Switzerland, and Wiley-VCH Weinheim, Germany, 2002, (1-413). |
2 | [2] "Heterocyclic Chemistry", J. A. Joule and G. F. Smith. University of Manchester. Van Nostrand Reinhold Company, New York, 1972, (1-361). |