How to cite a patent (or patent application) varies depending on the style manual required by each journal or discipline.
ACS format
Patent Owner 1; Patent Owner 2; etc. Title of Patent. Patent Number, Date.
ACS examples
Petrovick, P.R.; Carlini, E. Antiulcerogenic Preparation from Maytenus ilicifolia and Obtaintion Process. Br. Patent PI 994502, March 6, 1999.
Lenssen, K.C.; Jantscheff, P.; Kiedrowski, G.; Massing, U. Cationic Lipids with Serine Backbone for Transfecting Biological Molecules. Eur. Pat. Appl. 1457483, 2004.
APA format
Inventor(s). (Year). Patent Title (Patent Number). Source.
Notes: the patent number should include the jurisdiction. A URL is optional.
APA examples
Nilsen, K.D., & Schmidt, W. (1996).System And Hardware Module For Incremental Real Time Garbage Collection And Memory Management (US Patent No. 5,560,003). U.S. Patent and Trademark Office.
Lenssen, K.C., Jantscheff, P., Kiedrowski, G., & Massing, U. (2004). Cationic lipids with serine backbone (European Patent Application No. 1457483). European Patent Office.
Chicago format
Names, Creator. Patent title. Patent number, and year of filing.
Chicago example
Iizuka, Masanori, and Hideki Tanaka. Cement admixture. US Patent 4,586,960, filed June 26, 1984, and issued May 6, 1986.
CSE style offers 2 formats that basically only change where the date appears in the citation.
Name-date format
Author(s), inventors; patent holder, assignee. Date. Title of patent. Country issuing the patent country code patent number. Extent.
Name-date example
Blanco EE, Meade JC, Richards WD, inventors; Ophthalmic Ventures, assignee. 1990 Nov 13. Surgical Stapling System. United States patent US 4,969,591.
Citation-sequence and citation-name format
Author(s), inventors; patent holder, assignee. Title of patent. Country issuing the patent country code patent number. Publication date. Extent.
Citation-sequence example
Blanco EE, Meade JC, Richard WD, inventors; Ophthalmic Ventures, assignee. Surgical Stapling System. United States patent US 4,969,591. 1990 Nov 13.
This style manual does not specifically mention how to cite a patent; however, it can be extrapolated based on the typical MLA style for other types of materials.
MLA format
Last Name, First Name. "Patent name." Patent XXX. Date.
Note: date must be in Day Month Year format.
MLA example
Smith, Fredrick. "Unhinged door." US Patent 1,111,111. 31 May 1970.
This is based on ISO Standard 690:2010(E), Information & Documentation - Guidelines for Bibliographic References and Citations to Information Resources, section 15.9 recommends patents be cited similar to a contribution within a journal. The first element listed should be the name of the applicant creator, followed by the title of the patent. The country name or code and the official designation of the series within which the patent resource is numbered should follow. The patent serial number should suffice as numeration.
ISO Style examples
Douglass, Elias B. Cow Milker. US Patent 361,213. 1887.
Philip Morris, Inc. Optical Perforating Apparatus and System. European patent application 0021165 A1. 1981-01-07.
Winget Ltd. Detachable Bulldozer Attachment for Dumper Vehicles. Inventor: Reginald John England. 8 March 1967. Appl: 10 June 1963. Int. Cl: E02F 3/76. GB Cl: E1F12. GB Patent Specification 1060631.