TITLE: Hsiung on the Complex Structure of $S^6$
QUESTION [22 upvotes]: In 1986 C. C. Hsiung published a paper "Nonexistence of a Complex Structure on the Six-Sphere" and in 1995 he even wrote a monograph "Almost Complex and Complex Structures" to further elaborate on his proof.
Yet answers to the 2009 question on this site all agree that the existence of complex structures on $S^6$ is still an open problem. Some recent preprints answering the question with opposite answers are also cited there.
I would like to know if there are any known mistakes in Hsiung's approach and if so I would appreciate some reference to a paper that points them out.

REPLY [3 votes]: There was a paper published in China (1987?) by Dong (and Guan).
It gave a reason why Hsiung was wrong. That was basically
the note of Guan when he sat in a talk of Hsiung. Dong came late and missed
the talk. Guan gave him his note ant told him that the proof was wrong. After
Guan left to America, Dong published the note and added his own
proof that there is no complex structure on S^6. After
Guan received Dong's note, he warned him about his mistake.
But it was too late and the note was published under the joint
authors Dong and Guan. Later on Guan met Hsiung in Lehigh University.
Hsiung showed Guan his book and said that Yau said that his proof
is correct. Guan again told Hsiung about his mistake without
any conclusion. It is more like politics to Guan.