Rolf Dahlgren, who followed Huber's concepts on structure, had followed Takhtajan in using the term Lilianae in his 1977 classification although many of his contemporaries continued to use the older Liliiflorae. Clifford provides a comparison between Takhtajan and the Cronquist system at that time. Later, in 1980 Dahlgren reverted to Liliiflorae, explaining he was following the example of Robert Thorne (1968, 1976) since this had precedence over Cronquist (1968) and Takhtajan (1969). In his subsequent books on the monocotyledons, only Liliiflorae was used. Following Rolf Dahlgren's death in 1987 his wife, Gertrud Dahlgren, continued their work and published a further revision in 1989 that reverted to Lilianae.