APA

Freedman R. W., Lang H. W., . (1968). A comparison of infrared and gas chromatographic methods for determination of methane in mine air. [Washington, DC]: Bureau of Mines, U.S. Dep. of the Interior.

Chicago

Freedman R W, Lang H W, . 1968. A comparison of infrared and gas chromatographic methods for determination of methane in mine air. [Washington, DC]: Bureau of Mines, U.S. Dep. of the Interior.

Harvard

Freedman R. W., Lang H. W., . (1968). A comparison of infrared and gas chromatographic methods for determination of methane in mine air. [Washington, DC]: Bureau of Mines, U.S. Dep. of the Interior.

MLA

Freedman R W, Lang H W, . A comparison of infrared and gas chromatographic methods for determination of methane in mine air. [Washington, DC]: Bureau of Mines, U.S. Dep. of the Interior. 1968.