With the international following for her Outlander time-travel series, American writer Diana Gabaldon has garnered some insights into the variations on book tours around the world.

"It's real grind," Gabaldon admits. "But I said to the publisher, 'It's part of the job. When a book gets to this phase, this is what you do for it. You expect your book to support you; you'd better support your book."

The Gabaldon phenomenon is based on her yarns about a 20th-century English doctor, Claire Randall, who travels back in time 200 years and meets and marries a manly Highland Scot, Jamie Fraser.

Since the series' beginning 15 years ago, the first five books -- Outlander, Dragonfly in Amber, Voyager, Drums of Autumn and The Fiery Cross -- have sold more than 12 million copies.

The latest instalment, A Breath of Snow and Ashes (Doubleday Canada, $39.95), finds the couple and their clan of 18th- and 20th-century friends and relatives in North Carolina on the eve of the American Revolution.

"There's certainly one more book after that -- possibly two -- because as I said to my husband, I took three books to deal with the Jacobite rising of (17)45, which was a war that lasted six months and had three battles. I'm not sure how long it will take for me to get through the American revolution," Gabaldon says with a laugh.

A Breath of Snow and Ashes is centred on some lesser-known events from the 1770s. Since the Highlanders settle in North Carolina, Gabaldon focuses on the revolution's southern campaign, rather than the action around Boston and Philadelphia.

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