Whitney (a)-faults which are hard to detect
Annales scientifiques de l'École Normale Supérieure, Série 4, Volume 12 (1979) no. 4, p. 465-471
@article{ASENS_1979_4_12_4_465_0,
     author = {Kambouchner, Anne and Trotman, David},
     title = {Whitney $(a)$-faults which are hard to detect},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     publisher = {Elsevier},
     volume = {Ser. 4, 12},
     number = {4},
     year = {1979},
     pages = {465-471},
     doi = {10.24033/asens.1372},
     zbl = {0456.58003},
     mrnumber = {81g:58002b},
     language = {en},
     url = {http://www.numdam.org/item/ASENS_1979_4_12_4_465_0}
}
Kambouchner, Anne; Trotman, David J. A. Whitney $(a)$-faults which are hard to detect. Annales scientifiques de l'École Normale Supérieure, Série 4, Volume 12 (1979) no. 4, pp. 465-471. doi : 10.24033/asens.1372. http://www.numdam.org/item/ASENS_1979_4_12_4_465_0/

[1] D. J. A. Trotman, Counterexamples in Stratification Theory : Two Discordant Horns, Real and Complex Singularities, P. HOLM, Ed. (Proceedings of the Nordic Summer School/Symposium, Oslo, 1976, Sijthoff and Noordhoff, 1977, pp. 679-686). | Zbl 0378.57012

[2] D. J. A. Trotman, Geometric Versions of Whitney Regularity for Smooth Stratifications (Ann. scient. Éc. Norm. Sup., Vol. 12, 1979, pp. 461-471). | Numdam | MR 81g:58002a | Zbl 0456.58002