1. Restriction and modification system;Wilson;Annual Review of Genetics,1991
2. A.P.I. Systems S.A, La Balme Les Grottes, 3890 Montalieu Vercill, France
3. Enterotube, F, Hoffman La Roche and Cie S.A, Diagnostica, Basle, Switzerland
4. APILAB Plus, A.P.I. Systems S.A, La Balme Les Grottes, 3890 Montalieu Vercill, France