London, England (CNN) -- A British auction house plans to sell off newly discovered sketches done by Adolf Hitler when he was a struggling student trying desperately to get into art school.

The 12 charcoal and crayon sketches cover "typical student subjects" and don't display a great deal of promise, Mullock's Auctioneers said. They include two drawings of an elderly woman thought to be Hitler's mother, as well as studies of objects, landscapes, models, and even a Roman senator.

All are signed and some even have Hitler's Vienna address, Mullock's said.

The sale also includes the original portfolio in which Hitler kept the sketches, which is signed and has his address, Mullock's said.

"They look quite typical of an aspiring student hoping to get into art school -- tentative and not very certain about his perspective when he's using pencil and pen, making basic errors by getting the top and the bottom of a candlestick wrong in relation to each other, and so on," said Michael Liversidge, emeritus dean of arts at Bristol University in England.

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The sketches lack technical skill but are "not so bad that one can't imagine him learning.

"But there's not latent genius here, and not much beyond a moderate school grade," Liversidge said. "Probably if the artist was at school today you wouldn't encourage him to keep the subject up."

The sketches have been owned by a professional artist who had them for years in his own collection and for his own interest, said Richard Westwood-Brookes, the historical documents expert at Mullock's. The artist brought the works to Mullock's attention.

Mullock's plans to auction the sketches April 15 in Ludlow, England, about 125 miles northwest of London. They're expected to bring between £4,000 and £6,000 (about $6,100 and $9,100) each, the auction house said.

The drawings all date from around 1908 and 1909, when Hitler was a "penniless dropout" trying to get accepted into the prestigious Vienna Academy of Fine Arts to train as a professional artist, Mullock's said.

The school rejected him twice, so Hitler hung around the city, trying to make a living producing watercolors to sell to tourists, Mullock's said.

The rejection by the academy may have had huge implications for Hitler later in life, Westwood-Brookes said.

"Many believe that it was this rejection that turned his mind and unleashed the monster within him, which was to bring forth so much evil on the world," he said. "... In a sense, therefore, the academic decision of the art establishment in Vienna can go down as one of the most monumental decisions in all of history."

Nevertheless, Westwood-Brookes said, "On the evidence of these sketches, you can see why the Vienna Academy turned him away."