Volk, O. H., Botanische Anstalten d. Univ., Germany

• Vol 20, No 1 (1990) - Original Research
  Studies in the genus Riccia (Marchantiales) from southern Africa. 15. R. hirsuta and R. tomentosa, sp. nov., two distinct species previously treated as one
  Abstract  PDF
• Vol 16, No 1 (1986) - Original Research
  Studies in the genus Riccia (Marchantiales) from southern Africa. 3. R. schelpei, a new species, in the new subgenus Chartacea
  Abstract  PDF
• Vol 16, No 2 (1986) - Original Research
  Studies in the genus Riccia (Marchantiales) from southern Africa. 4. Three endemic species, R. natalensis, R. microciliata sp. nov. and R. mammifera sp. nov.
  Abstract  PDF
• Vol 16, No 2 (1986) - Original Research
  Studies in the genus Riccia (Marchantiales) from southern Africa. 5. R. rosea, a new species
  Abstract  PDF
• Vol 16, No 2 (1986) - Original Research
  Studies in the genus Riccia (Marchantiales) from southern Africa. 6. R. hirsuta, a new species, in a new section
  Abstract  PDF