English summary on page 92 as follows: Two opinions: 1. The peoples of South East Asia (the Viet among them) had root crop as food before rice cultivation. 2. The form of slash-burn field in Viet Nam should evolve toward three trends: - Up to the increasingly steepy hill slopes while using rude implements such as axes, bush whackers, perforating sticks, nhip (reapping knife), bamboo clips, or empty hands. It's the disintegrating stage of the slash-burn form. - Into slash-burn fields relatively stable
being damed they wilkl serve as "field waiting for rain", such as fields on hill slope, tiered fields. - Into intensivegardens, especially at piemont zone. From the primitive garden one passed straight into the form of inundated fields. The mountainous peoples have made acquaintance with glutinous rice prior to ordinaryrice. The "ghost rice" is a kind of domesticated rice being left uncultivated that grows itself afterwards: but the practice of collecting ghost rice for ancestors cult should suggest a period of collecting it for food.