[1]Heterocycles,1980,vol.14,p.287-290
[1]JournalofHeterocyclicChemistry,1986,vol.23,p.1481-1485
[1]Heterocycles,1985,vol.23,p.2327-2333
[1]JournalofHeterocyclicChemistry,1983,vol.20,p.951-955
[2]EuropeanJournalofOrganicChemistry,2005,p.4141-4153
[1]Chemicalandpharmaceuticalbulletin,1989,vol.37,p.1477-1480