https://digital.library.lse.ac.uk/Documents/Detail/report-on-the-census-of-production-for-1991.-pa1001-introductory-notes/458239
Report on the Census of Production for 1991. PA1001 Introductory Notes - LSE Digital Library
https://digital.library.lse.ac.uk/Documents/Detail/report-on-the-census-of-production-for-1992.-pa1001-introductory-notes/459706
Report on the Census of Production for 1992. PA1001 Introductory Notes - LSE Digital Library
https://digital.library.lse.ac.uk/Documents/Detail/report-on-the-census-of-production-for-1989.-pa1001-introductory-notes/457288
Report on the Census of Production for 1989. PA1001 Introductory Notes - LSE Digital Library