What book should I buy?

I’ve decided to treat myself to a book, but as usual I have an interest in too many languages, and can’t decide which to purchase. Here’s my shortlist:

Teach Yourself Complete Russian by Daphne M. West.
" " " Polish
" " " Mandarin Chinese
Colloquial Italian: The Complete Course for Beginners.

I enjoy slavic languages, which is why I have included the Russian and Polish books. Last time I was on Chinese LingQ, I loved the sound and simplistic nature of Chinese grammar (not to mention it’s fun trying to guess what cheap tattoos actually mean!). I did a year of Italian but the course stopped. Now I can’t remember much, but would like to know some more. I do already have a book on Italian and Russian, but I’d like to know if the ones I mentioned above are worthy of investing in.

What one would you go with? Have you used any of these before? What one is “the best”?

Have you tried your local library? Ours has a great selection of language learning material. Perhaps yours can help you to narrow down your list?

I’m not actually a member, but I suppose it will save me some money. Next time I’m there, I think I’ll sign up.

I’ve just ordered the Chinese book. I’m looking forward to it arriving.