| Auteur(s) | Dochkova, B., Atanassov, N. and Vassileva, E. |
| Jaar | 1987 |
| Titel | Species composition and numbers of the wild bees (Hymenoptera, Apoidea) - pollinating on the forage loants from the region of Pleven. Acta Zoologica Bulgarica 35 : 34-43. |
| Auteur(s) | Dochkova, B., Atanassov, N. and Vassileva, E. |
| Jaar | 1987 |
| Titel | Species composition and numbers of the wild bees (Hymenoptera, Apoidea) - pollinating on the forage loants from the region of Pleven. Acta Zoologica Bulgarica 35 : 34-43. |