edited by Gerald W. Whitted
Pan American World Airways, 1971
Buku Referensi
edited by Gerald W. Whitted
Pan American World Airways, 1963
Buku Referensi
Lambert, Brian W.
American Society for Training & Development, 2009
eBooks
by Steven L. Spiegel [and others]
Thomson Wadsworth, 2005
Buku Teks
Price, Margaret M.
Mc Graw-Hill, 1994
Buku Teks