1. Antonetti PLE and Pinon J (1993) Somaclonal variation within poplar. Plant Cell Tiss Org Cult 35: 99?106
2. Barrocka KH, Bans H, Lontke E and Sievert F (1984) Tissue culture as a tool for in vitro mass propagation of aspen. Z Pflanzenzücht 94: 340?343
3. Brutovská R, Cellárová E, Davey MR, Power JB and Lowe KC (1994) Stimulation of shoot regeneration from seedlings of Hypericum perforatum L. by Pluronic F-68. Acta Biotechnol 4: 371?377
4. Cawrse N, de Pomerai DI and Lowe KC (1991) Effects of Pluronic F-68 on 2-deoxyglucose uptake and amino acid incorporation into chick embryonic fibroblasts in vitro. Biomed Sci 2: 180?182
5. Douglas GC (1989) Poplar (Populus spp.). In: Bajaj YPS (ed) Biotechnology in Forest and Agriculture, Vol 5, Trees II, pp 301?323. Berlin: Springer-Verlag