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Wikipedia article
'Ma Su Chen' aka 'Rebel Boxer' or 'Bloody Struggle' is a 1972 Hong Kong film"Ma Su Chen (1972)". 'List of Hong Kong films of 1972'. Retrieved 6 June 2016 directed and co-written by Ting Shan-hsi who also directed and wrote the film Furious Slaughter 1972. It is a martial arts film that stars Nancy Yen, Jimmy Wang Yu, and Sally Chen. It's a sequel to Furious Slaughter 1972 in which Jimmy Wang Yu plays the lead role. It was released in Hong Kong on 14 June 1972 but in Taiwan on 30 May 1972.[https://www.imdb.com/title/tt0074224/releaseinfo?ref_=tt_dt_dt "Ma Su Chen (1972) - ReleaseInfo"].'IMDb'. Retrieved 5 June 2016
Apparently, the cast mentioned in Rotten Tomatoes is based on another version of Ma Su Chen (1972) because it listed two additional stars, Richard Harrison and Hwang Jang Lee, not found in other cast list of the same movie.
Plot
Believing that her brother has been murdered, a martial artist Ma Su Chen (Nancy Yen) sets out to avenge him. Ma Su Chen is also a doctor. Later part of the movie, both of them fought together as a brother-sister team against their common enemy and defeated them.
Cast
[http://hkmdb.com/db/movies/view.mhtml?id=5322&display_set=eng "Ma Su Chen (1972)"]. 'hkmdb'. Retrieved 31 May 2016[http://www.hkcinemagic.com/en/movie.asp?id=7858 "Ma Su Chen (1972)"]. 'Hong Kong Cinemagic'. Retrieved 31 May 2016