It was dicovered by a Yugoslav chemist called Milutin Stefanovic.
His discovery was first presented at the Eighth International Symposium in India on the Chemistry of Natural Products, held in New Delhi, India, 6-12 February 1972 (D. Jeremić, A. Jokić, A. Behbud and M. Stefanović, “New Type of Sesquiterpene Lactones Isolated From Artemisia Annua L. – Ozonide of Dihydroarteannuin”, 8th International Symposium on The Chemistry of Natural Products, New Delhi, 1972, C-54, 221). One year later it was published in a well known peer reviewed jounal (D.Jeremić, A. Jokić, A. Behbud, M. Stefanović, A new type of sesqiterpene lactone isolated from Artemisia annua L., Tedrahedron Letters 1973 Vol 14- Iss 32, 3039-3042), The molecule was further described in 1974 (Uskoković MR, Williams TH, Blount JF. The structure and absolute configuration of arteannuin B. Helvetica chimica acta 57:3 1974 Apr 27 pg 600-2).
One of the first Chinese papers relating the discovery of artemisinins was published much later, in 1979, by a team of Chinese scientists. Tu Youyou was not the main author but co-author. (Liu JM, Ni MY, Fan JF, Tu YY, Wu ZH, Wu YL, Chou WS,197, Structure and reaction of Arteannuin. Acta Chim Sin 37:129–143). This paper refers to the discovery of artemisinin by M Stefanovic.
Hereafter an answer I received form our partner Pr Zorica Juranicz at Belgrade: Many thanks for the nice letter regarding the work on artemisinin, of the professors from Serbia. It is so good that you appreciate their scientific work. I know professor Solaja and he told me about this story. Best regards, Zorica