If you ever face the Dragon Sicilian you need a way to tackle it and the Yugoslav Attack is a good method. But, the problem is a well booked up opponent won't let you open the h-file and those devastating attacks you see in the books never materialize.
The Levenfish Variation (6. f4) is named after Grigory Levenfish who recommended it in the 1937 Russian Chess Yearbook. Today, it's almost disappeared as black has found ways to exploit the slight weakening of control of e4 which can no longer be supported by a P.
Nevertheless there are many traps, and if black doesn't know theory, disaster comes quickly in a variety of ways. White prepares 7.e5 attacking Black's f6-knight and it used to be that 6... Nc6 or 6... Nbd7 were considered mandatory.
However, it has transpired that after the frequently seen 6... Bg7, which was originally thought to be a serious mistake, black's game is quite playable. Even so, while technically sound, it almost always turns out disastrous. Black does much better not to let white play his P to e5. For an interesting comparison of the statistics on the Levenfish go to Chesstempodotcom and Chessgamesdotcom.