1. Behrens HM, Volkmann D, Sievers A (1986) Norderney Symp Sci Res German Spacelab Mission D1, pp 454-462.
2. Brown AH, Chapmann DK (1984) Science 225:230–232.
3. Brown AH, Chapman DK, Liu SWW (1974) Bio Science 24:518–520.
4. Cowles JR, Scheid HW, LeMay R, Peterson C (1984) Ann Bot (London) 54,Supp 3:33–48.
5. Cowles JR, Jahns G, LeMay R, Omran R (1986) Plant Physiol 80,Suppl 4:9.