How to cite a patent (or patent application) varies depending on the style manual required by each journal or discipline.
ACS style (3rd edition, 2006, page 310)
Format: Patent Owner 1; Patent Owner 2; etc. Title of Patent. Patent Number, Date.
Example 1: Petrovick, P.R.; Carlini, E. Antiulcerogenic Preparation from Maytenus ilicifolia and Obtaintion Process. Br. Patent PI 994502, March 6, 1999.
Example 2: Lenssen, K.C.; Jantscheff, P.; Kiedrowski, G.; Massing, U.Cationic Lipids with Serine Backbone for Transfecting Biological Molecules. Eur. Pat. Appl. 1457483, 2004.
APA style (6th edition, 2009, page 224)
Format: Inventor(s).(Year). Patent Number. Source.
(Patent number is in italics.)
Example 1: Petrovick, P.R., Carlini, E.(1999).US Patent No. 1,123,445. Washington, DC: U.S. Patent and Trademark Office.
Example 2: Lenssen, K.C., Jantscheff, P., Kiedrowski, G., Massing, U. (2004). European Patent Application 1457483.
Chicago Manual of Style (16th edition, 2010, section 14.230)
Format: Names, Creator.Patent title. Patent number,and year of filing.
Example: Iizuka, Masanori, and Hideki Tanaka. Cement admixture. US Patent 4,586,960, filed June 26, 1984, and issued May 6, 1986.
CSE style (8th edition, 2014,section 18.104.22.168)
CSE style offers 2 formats that basically only change where the date appears in the citation.
Author(s), inventors; patent holder, assignee. Date. Title of patent. Country issuing the patent country code patent number. Extent.
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.
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.
Format: Last Name, First Name. "Patent name." Patent XXX. Date.
(The date must be in Day Month Year format.)
Example: Smith, Fredrick. "Unhinged door." US Patent 1,111,111. 31 May 1970.
Non-U.S. publications may use an ISO style. 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.