CUNHA, Marina Silva da <br/><br/>
Valores-trabalho e preços de produção em um sistema econômico sraffiano com renda extensiva 

 - São Paulo :  Editora 34,  abr./jun.  2000 
<br/><br/> This article develops an extension of sraffian’s approach, considering a model where the economy is divided into two sectors, the industrial and the agricultural. From a system in physical units it is possible to determine labour values and prices of pro-duction. The paper analyses the determination of labour values using Morishima’s suggestion, with linear programming. It is shown that in an economic system with land scarcity the existence of positive surplus-value is not a sufficient condition for positive profits