Billett MF. Scotland's soils: Research issues in developing a soil sustainability strategy. Perth: Scottish Natural Heritage; 1994 pp. 25-29.

Black KE, Lowe JAH, Billett MF, Cresser MS. Observations on the changes in nitrate concentrations in seven upland moorland catchments in north eastern Scotland. Water Research. 1993  ;27:1195-1199.

Billett MF, Parker-Jervis F, FitzPatrick EA, Cresser MS. Forest soil chemical changes between 1949/50 and 1987. Journal of Soil Science. 1990  ;41:133-135.

Billett MF, FitzPatrickm EA, Cresser MS. Long term changes in the acidity of forest soils in north east Scotland. Soil Use and Management. 1988  ;4:102-107.