Gingerelli, Dain; Michels, James Manning; Everitt, Charles. [Harley-Davidson a Google Books365 Motorcycles You Must Ride] (en anglès). Minneapolis, Minn.: MBI Publishing, 2010, p. 91. ISBN 978-0-7603-3474-4.
Field, Greg. Darwin Holmstrom (ed.). The Myth of Harley VS. Japan (en anglès). St. Paul, Minn.: MotorBooks International, 1/9/2002, p. 206–207. ISBN 0-7603-1155-2 [Consulta: 26 desembre 2012]. «Before the tariff was even implemented, Harley offered to drop its bid if the Japanese would give Harley loan guarantees of about $15 million to fund development of the Nova project.»
«Harley talks to Big Four, Looks to Triumph» (en anglès). Cycle World, 23, gener 1984. «The enactment of the import tariff... hasn't kept the two sides – Harley-Davidson and Japan's Big Four manufacturers—from talking to each other... [Harley has] met with representatives of Honda, Yamaha, Suzuki and Kawasaki to discuss possible alternatives to the tariff.»
Field, Greg. Darwin Holmstrom. Father of the Softail (en anglès). St. Paul, Minn.: MotorBooks International, 1/9/2002, p. 242–243. ISBN 0-7603-1155-2 [Consulta: 26 desembre 2012].
Field, Greg. Darwin Holmstrom. Chapter 8: The Evolution Era (en anglès). St. Paul, Minn.: MotorBooks International, 1/9/2002, p. 259, 261. ISBN 0-7603-1155-2 [Consulta: 26 desembre 2012].
Field, Greg. Darwin Holmstrom. Chapter 8: The Evolution Era (en anglès). St. Paul, Minn.: MotorBooks International, 1/9/2002, p. 267. ISBN 0-7603-1155-2 [Consulta: 26 desembre 2012]. «For 2000 came the FXR4, which was the last of two distinguished breeds: the last of the rubber-mounted FXR models and the last of the Evo-powered Harley Big Twins.»
Girdler, Allan. «A Brief Harley History». A: Harley-Davidson: The American Motorcycle (en anglès). St. Paul, Minn.: MotorBooks International, 1 novembre 2003, p. 10–11. ISBN 0-7603-1651-1 [Consulta: 19 desembre 2012]. «Like the prototypes and the first fifty or so examples made, it had a single-cylinder engine with atmospheric intake valve; that is, when the piston went down for the intake stroke, the valve was sucked open and when it started back up, the valve was compressed shut.»
Rafferty, Tod. «Model 9 1913». A: The Illustrated Directory of Harley-Davidson Motorcycles (en anglès). St. Paul, Minn.: Salamander Books, 2001, p. 44 47. ISBN 0-7603-1126-9 [Consulta: 19 desembre 2012]. «Of course the single had benefited from the development work devoted to its big brother. Mechanically operated intake valve, lighter alloy piston and improved carburetion were included in the package.»
Girdler, Allan; Hackett, Jeff; Woods, Bob. «Harley-Davidson Timeline». A: Harley-Davidson (en anglès). St. Paul, Minn.: MotorBooks International, 24/5/2006, p. 78. ISBN 978-0-7603-2332-8 [Consulta: 19 desembre 2012]. «1926: Harley-Davidson reintroduces single-cylinder motorcycles, for the first time since 1918.»
Hatfield, Jerry. Darwin Holmstrom. The Flathead Era (en anglès). St. Paul, Minn.: MotorBooks International, 1/9/2002, p. 47–65. ISBN 0-7603-1155-2 [Consulta: 26 desembre 2012]. «For 1930, the factory brought out a 500-cc (30.5-cubic inches) flathead single. The 350-cc singles were offered for the seasons of 1926 through 1930 in both flathead and overhead versions, and as flatheads only from 1931 through 1934.»
Waheed, Adam «Harley-Davidson Finalizes Sale of MV Agusta» (en anglès). Motorcycle USA, agost 6, 2010. Arxivat de l'original el d’octubre 19, 2010 [Consulta: 18 setembre 2010]. «American motorcycle manufacturer Harley-Davidson announced today that it has completed the sale of MV Agusta for an undisclosed amount to Claudio Castiglioni and his wholly owned holding company, MV Agusta Motor Holding, S.r.l.»
«The Holiday Rambler RV: A Historic Look» (en anglès). Pedata RV Center. Tucson, AZ USA: Pedata Resales. Arxivat de l'original el 15/7/2011. [Consulta: 17 maig 2011]. «In 1996, the Holiday Rambler RV line became one of the prestigious lines backed by Monaco Coach Corporation.»
Lemmy. «Motorcycle tariffs and Harley-Davidson Lessons from the last time» (en anglès). RevZilla.com. RevZilla, 05-03-2018. [Consulta: 21 setembre 2018]. «Harley again requested federal assistance in 1982, this time citing Article XIX of the General Agreement on Tariffs and Trade of 1974, better known as 'the escape clause.'»
«The Holiday Rambler RV: A Historic Look» (en anglès). Pedata RV Center. Tucson, AZ USA: Pedata Resales. Arxivat de l'original el 15/7/2011. [Consulta: 17 maig 2011]. «In 1996, the Holiday Rambler RV line became one of the prestigious lines backed by Monaco Coach Corporation.»
Waheed, Adam «Harley-Davidson Finalizes Sale of MV Agusta» (en anglès). Motorcycle USA, agost 6, 2010. Arxivat de l'original el d’octubre 19, 2010 [Consulta: 18 setembre 2010]. «American motorcycle manufacturer Harley-Davidson announced today that it has completed the sale of MV Agusta for an undisclosed amount to Claudio Castiglioni and his wholly owned holding company, MV Agusta Motor Holding, S.r.l.»
«Former York Naval Ordnance Plant» (en anglès), 2005. [Consulta: maig 14, 2008]. «Harley-Davidson has taken their environmental responsibilities very seriously and has already made substantial progress in the investigation and cleanup of past contamination. Proof of Harley's efforts can be found in the recent EPA determination that designates the Harley property as 'under control' for cleanup purposes. This determination means that there are no serious contamination problems at the facility. Under the new One Cleanup Program, Harley, EPA, and PADEP will expedite the completion of the property investigation and reach a final solution that will permanently protect human health and the environment»
