session "Lex" = HOL +
  theories [document = false]
	"Lexer" 
        "Simplifying"
        "Sulzmann" 


session Paper in "Paper" = Lex +
  options [document = pdf, document_output = "..", document_variants="paper"]
  theories 
    "~~/src/HOL/Library/LaTeXsugar"
    "Paper"
  document_files
    "root.bib"
    "root.tex"