TY  - GEN
AU  - Heuts,M.J.
TI  - The phenotypical variability of Gasterosteus aculeatus (L.) populations in Belgium : : its bearing on the general geographical variability of the species 
PY  - 1947///
CY  - Utrecht
PB  - W. de Haan, 
N1  - Tav. di studio SZN
ER  -