A mathematical text, borrowed from the library at the Bendigo campus in 1978, was recently mailed back to the university, complete with a note.

Jonathon Newman, of the university's library business services, said the book's return was completely unexpected.

"It's by far the oldest return I think we've had at the library," Mr Newman said.

He said the borrower had been intent on seeing O. D. Anderson's Time Series Analysis and Forecasting: The Box-Jenkins Approach returned to the Bendigo campus.

Mr Newman believed the library still had some copies of the text on its shelves.

It is not known whether the long-lost copy has rejoined them.

"The title is just so funny in the context of it going missing for 43 years," Mr Newman said.

Any overdue penalty the book would have incurred was waived.

He said the book's return had been cause for excitement among the library staff.

"We love this sort of thing. It's great. It makes you feel like you're providing a service people really care about," Mr Newman said.

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He wanted to thank the borrower for returning the book.

"It's a really kind act," Mr Newman said.

"We really don't expect someone to go out of their way to do something like that."

He said anyone with an overdue library book should feel free to drop it in, no matter how long it had been on loan.

"You can always drop it in the return chute," Mr Newman said, for anyone feeling self-conscious.

"We'll take them all."

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