grassetto = Testo principale
   Cap.        grigio = Testo di commento

 1      I(12) |  Variation of Animals and Plants under Domestication (Variazioni
 2     II(14) |  Variation of animals and Plants under Domestication (Variazione
 3      V(52) |  Variation of Animals and Plants under Domestication, capit. ix,
 4      V(56) | Variations of Animals and Plants under Domestication, cap xvii,
 5     VI(67) |  Variation of Animals and Plants under Domestication, capitolo
 6    VII(75) |  Variation of Animals and Plants under Domestication, cap. xi,
 7    VII(76) |        fatto nella mia Variation under Domestication (Variazione
 8     IX(91) |                        Variation under Domestication, cap. xvii,
 9      X(141)|                        Variation under Domestication (Variazione
10    XII(183)|                        Variation under Domestication, ecc., cap.
11    XII(190)|                        Variation under Domestication, ecc., cap.
12    XII(197)|  Variation of Animals and Plants under Domestication, cap. xii,