%0 Journal Article %A Piga, Claudio %A Vivarelli, Marco %D 2006 %T Internal and external R&D: a sample selection approach %U https://repository.lboro.ac.uk/articles/journal_contribution/Internal_and_external_R_D_a_sample_selection_approach/9491633 %K untagged %K Economics %K Economics not elsewhere classified %X Internal and external R&D: a sample selection approach %I Loughborough University