1. Braun , A. 1860 Über Polyembryonie und Keimung von Coelebogyne Abhandl. Akad. Wiss. Berlin Phys. Kl. 107 263
2. Haploid-diploid twin embryos in Lilium and Nicotiana;Cooper;Amer. Jour. Bot.,1943
3. Genetic and cytological investigations on Asparagus officinalis L;Flory;Genetics,1932
4. Erbliche Polyembryonie bei Linum usitatissimum;Kappert;Biol. Zentralblatt,1933
5. Haploids and haplo-diploids among hybrid twin seedlings in wheat;Kasparyan;C. R. (Doklady) Acad. Sci. U. R. S. S.,1938