found: Work cat.: 2001023266: Love, T.M. L-birds : American combat liaison aircraft of World War II, c2000(light aircraft, often simply military versions of civil aircraft, used for artillery spotting, liaison with ground forces, short-range low-altitude reconnaissance, aerial observation, short hops for commanders or wounded, etc.)
found: Quick dict. weapons(Observation aircraft)
found: Bright, C. Historical dict. of the U.S. Air Force, 1992(liaison aircraft; used for battlefield reconnaisance, utility, and artillery spotting and correction)
found: Rand McNally encyc. of military aircraft, 1914-1980, 1981:p. 341 (Army co-operation aircraft) p. 490 (observation and liaison planes)
found: Waters, A. All the U.S. Air Force airplanes, 1907-1983, 1983:p. 221 (liaison planes; L designation used 1942 to 1962)