Denken in de toekomst : 25 jaar Stichting Grafische Bedrijfsfondsen / [tekst Wim Hijmans] Internal ballistics of solid-fuel rockets : military rockets using dry-processed double-base propellant as fuel / by R.N. Wimpress ; with a pref. by B.H. Sage Ab origine flexibilis' : Luchtmacht Stafschool 1949-1991 / W.H. Lutgert eerste stap in Indië / [Wimpie Welfare]