Helfert, E. A. (1967). Techniques of financial analysis (Rev. ed.). R.D. Irwin.
Lua i Stíl Chicago (17ú heag.)Helfert, Erich A. Techniques of Financial Analysis. Rev. ed. Homewood, Ill.: R.D. Irwin, 1967.
Lua MLA (8ú heag.)Helfert, Erich A. Techniques of Financial Analysis. Rev. ed. R.D. Irwin, 1967.
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