Articles
The article a is used before the aspirate h (eg, a historic occasion) and nonvocalic y (eg, a ubiquitous organism). Abbreviations and acronyms are preceded by a or an according to the sound following (eg, a UN resolution, an HMO plan). (See also 14.8, Abbreviations, Agencies and Organizations.)
a hypothesis [h sound] |
a hematocrit [h sound] |
an ultraviolet source [u sound] |
an honorarium [o sound] |
a WMA report [d sound] |
an MD degree [e sound] |
a UV source [y sound] |
an NIH grant [e sound] |