The trouble with works of reference is that they never quite have what you're looking for. Or if they do, you can't find it, because it's not where you expect it to be. To find the date of Burns Night in the Encyclopaedia Britannica, for example, you have to look under "haggis", writes William Hartston.

The problem has been eased by the advent of the CD-rom, which lets you search for words ("Burns" and "night", for example) in the body of the text rather than only among the headwords. If it's there, you can find it. But is it there? I have been test driving some recent reference works to find out.

There are two things above all that I need to know: how many ducks are there in the world, and which country produces most bananas? Now the Oxford Reference Shelf (16 reference books on one CD-rom for £79.99), or the Oxford Compendium (four more reference works on a single CD-rom at the same price), ought surely to be able to provide the answers. On the subject of ducks, the Oxford Dictionary of Abbreviations informed me that DA, as well as being Dan-Air, Deputy Advocate and Doctor of Arts, could signify a "duck's arse" hairstyle. Or dk's arse, if dk is not the equally acceptable dark, dock or deck.

The Concise Dictionary of Business told me about lame ducks and the Compact Encyclopedia added information on some of the 200 species of duck, including eider, golden-eye, mallard, teal, merganser, pintail, pochard, shelduck, shoveler and wigeon. Then, for good measure, it threw in some stuff about Jemima Puddle-Duck, the "nodding duck" wave power generator, Bombay duck and Ibsen.

I learnt that le canard is a male French duck and la cane a female, either of which may provide a magret to eat.

In Germany, evidently a nation of prolific duckers, the verb to duck may be translated as ducken, tauchen, untertauchen or, most Teutonically, den Kopf einziehen. Italian admits to no ducking verb at all. The dictionaries of Law and Computing have nothing to say at all about ducks - or bananas - though the Pocket Oxford Dictionary mentions several more ducks, including gadwall and Muscovy, sitting and dead, as well as water off a duck's back, the stone-skimming game of ducks and drakes, and another meaning of duck as a strong fabric used for making trousers. I also learnt that ducks may make a harsh sound known as a "quack".

Passing quickly over the duck-billed platypus (with one hyphen, according to the Oxford Dictionary for Writers and Editors), we end with F W Harvey in the Dictionary of Modern Quotations: "From troubles of the world I turn to ducks Beautiful comical things."

Yet I am left still in ignorance about how many there are. I had no better luck with bananas, though I did learn that they are botanically berries, that they are examples of parthenocarpy, that a banana bond is an electron deficient bond holding B-H-B bridges in boranes, that the plantain is cooked and eaten green in Africa and the Caribbean, that all cultivated bananas are sterile, and that Irving Cohn and Frank Silver wrote "Yes! We have no bananas" in 1923. The nearest I came to discovering what I wanted to know was when the World Gazetteer told me that bananas are the second largest export of Somalia, mostly shipped to Italy.

I finally found the answers to both questions in Russell Ash's The Top Ten of Everything (Dorling Kindersley, £12.99), where, between tables of grape and mango-producing countries, I spotted India topping the banana league (ahead of Brazil and the Philippines), and before a panel of camel facts, I learnt that there are 580 million ducks in the world, mostly Chinese.

But it's not available on CD-rom, and, with "duck" and "banana" both absent from the index, it looks as though the publishers of this book might not really want us to know either.