Inhibitory Effect of Triterpenes from Crataegus pinatifida on HIV-I Protease - Min, Byung Sun; Jung, Hyun Ju; Lee, Jun Sung; Kim, Young Ho; Bok, Song Hae; Ma, Chao Mei; Nakamura, Norio; Hattori, Masao; Bae, KiHwan (Planta Medica, 1999)