Published in Gardens' Bulletin Singapore, in 1991, in volume 43, issue 1, pages 1-17

Published in Gardens' Bulletin Singapore, in 1991, in volume 43, issue 1, pages 19-21

Published in Gardens' Bulletin Singapore, in 1991, in volume 43, issue 1, pages 23-26

Published in Gardens' Bulletin Singapore, in 1991, in volume 43, issue 1, pages 27-38

Published in Gardens' Bulletin Singapore, in 1991, in volume 43, issue 1, pages 39-42