I have the book Super Baby FOod. It states that breast milk or formula should be the main source of nutrition for the first year. It suggests parents to give the breast or bottle first (maybe half a normal feeding) then the food then some more milk/formula after this. In my experience, my lo won't just eat a new food right off if she is hungry. She wants her milk first than she will try something else.
There are numerous sources on here, kellymom, dr.sears that explain how important it is that breast milk be the primary food for the first 12 months and that solids should NOT replace breastfeeding, but compliment it.