Erzsi, there are cookbooks galore, but I haven't ever purchased one. I tend to use the Internet for my pressure cooking forays along with the instructions that came with it.
Ms Vicky or Mrs Vicky or some such is one site that has a LOT of pressure cooking resources, recipe, etc. It's not always the easiest to use; when you want a recipe, you download the file that contains it and many others, such as all soups, rather than just seeing the recipe for pea soup, let's say. How could I have been wrong???? It's
MISS Vicky! She charges for some, but many are free.
Some of the recipe sites are decent sources, too. Recipezaar has more than Allrecipes, if I remember correctly. I have a Fagor (was very reasonably priced at Costco) and
their site has some recipes.
Over time, you get more comfortable making things up. I recently wanted stuffed cabbage, but didn't want to wait for hours, so decided to try the pressure cooker. It wasn't exactly right, but it was good and next time I'll know what to do different.
One thing I've found that's pretty important--cooking times are deceiving. It says 12 minutes and you think, WOW, I'll be eating in 15! But, it takes quite awhile to get to pressure before the thingee pops and you can start timing. Also, you have the time while it releases the pressure. It easily doubles or triples the time. Now I remember it, but initially everything was much later than I planned on having it ready.
One other tip - cooking things together doesn't always work. Take 15 bean soup. For some reason, it's not so noticable when you cook them slowly. In the PC, though, one variety takes 3 minutes and another 7 and another 13. By the time ALL of them are done, the first ones to be finished are exploded all over and are mush. I've learned that bean soup is excellent when made in it...when it's all one type of bean. Actually, as I type this, I don't even make the soup in the cooker - I cook the beans about 15% short of being done, then add the other ingredients and continue cooking regularly. It only takes about 20-30 minutes after the beans are ready and I have excellent soup.