Mafia Wars Italy is all about Gate Loot - an item obtained in one job that is required in another job.
The Severed Pinky (obtained and used in Roma) and Rail Ticket (obtained in Palermo, used in Venezia) are simple enough to master. One job drops the Gate Loot, and one other job that requires it.
It's not quite as simple when it comes to finding and using Smart Phones, Cooked Books, and Hidden Charges
These two Gate Loot Flowcharts highlight the jobs that drop - and the jobs that require - Smart Phones, Cooked Books, and Hidden Charges, as you make your way through Milano and Napoli.
The Smart Phone is Gate Loot for FIVE different jobs in Milano and Napoli!
You can get Cooked Books from two separate Milano jobs, and use them to find find Hidden Charges in a Napoli job. The Hidden Charges are then required Gate Loot for two other Napoli jobs.
*Cooked Books + Hidden Charges*
Remember - Mafia Wars Italy Regions 6, 7, and 8 - to be released soon - *may* require some of these five Gate Loot items. Or, as eventually happened in Las Vegas, maybe we'll be able to trade the Gate Loot when the later Regions go live. Either way, it can't hurt to stock up on more than the exact number you need to complete Ruby level in each Region...