Fears were raised for the 53-year-old Swedish citizen when he failed to contact family members after Chinese authorities said Tuesday that he had been released on October 17.
The Swedish foreign ministry announced on Tuesday that it had been informed of his release but was still trying to contact him.
Gui was one of five Hong Kong-based booksellers known for salacious titles about the lives of China's political elite who went missing in 2015 and resurfaced in detention on the mainland.
Olsson said Gui was in the eastern Chinese city of Ningbo and had been able to meet his mother and sisters, citing a source close to the publisher.
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When asked if she had received a call and whether she believed it was from her father, Angela told AFP: "A call did take place," without giving further detail about what was said.
"There are still many things that need to be clarified and I don't think we can jump to conclusions just yet," she said in an email.
"A few days ago, he personally called the Swedish consulate in Shanghai, in Swedish, and will apply for a new passport soon," he added, without revealing his sources.
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