B 500.482 I 1'1 b ode n, N.: A Hanaqell'ent-Approach to project appraisal and evaluation. \üth soecial reference to.non-directly productive projects. /l~it Tab. / -(Paris: l OECD (1978. l o 172 s. e Franz.Ausg.u.d.T.: Irnboaen: l'Appreciation et li~valuation ce projets ce ceveloppement. (Development centre studies.l