Askbrant, S. (1990). The concept of metabolisable energy for poultry: A study on effects of bird age, protein retained, level of feed intake, and endogenous excretions on dietary energy metabolised. Swedish University of Agricultural Sciences, Dept. of Animal Nutrition and Management.

Askbrant, Stefan. The Concept of Metabolisable Energy for Poultry: A Study on Effects of Bird Age, Protein Retained, Level of Feed Intake, and Endogenous Excretions on Dietary Energy Metabolised. Uppsala: Swedish University of Agricultural Sciences, Dept. of Animal Nutrition and Management, 1990.

Askbrant, Stefan. The Concept of Metabolisable Energy for Poultry: A Study on Effects of Bird Age, Protein Retained, Level of Feed Intake, and Endogenous Excretions on Dietary Energy Metabolised. Swedish University of Agricultural Sciences, Dept. of Animal Nutrition and Management, 1990.