Yong, S. R., Ung, A. T., Pyne, S. G., Skelton, B. W. & White, A. H. (2007). Syntheses of spiro[cyclopropane-1,32-oxindole]-2-carboxylic acid and cyclopropa[c]quinoline-7b-carboxylic acid and their derivatives. Tetrahedron, 63 1191-1199.
Yong, S. R., Ung, A. T., Pyne, S. G., Skelton, B. W. & White, A. H. (2007). Syntheses of spiro[cyclopropane-1,32-oxindole]-2-carboxylic acid and cyclopropa[c]quinoline-7b-carboxylic acid and their derivatives. Tetrahedron, 63 1191-1199.