APA

Howett G. L., . (1983). Size of letters required for visibility as a function of viewing distance and observer visual acuity. Washington: U.S. Department of Commerce.

Chicago

Howett Gerald L, . 1983. Size of letters required for visibility as a function of viewing distance and observer visual acuity. Washington: U.S. Department of Commerce.

Harvard

Howett G. L., . (1983). Size of letters required for visibility as a function of viewing distance and observer visual acuity. Washington: U.S. Department of Commerce.

MLA

Howett Gerald L, . Size of letters required for visibility as a function of viewing distance and observer visual acuity. Washington: U.S. Department of Commerce. 1983.