Just perseverance,Janpled.,Im afraid..While they are in leaf,get as many out as you can,but you will still miss some of the tiny bulbs..When you see the grass like foliage appearing again,keep digging them out. No good just tugging them,as sometimes you only get a bunch of leaves,and not the bulbs....also,cut off the flowers before they drop ..I've taken all mine off now..Don't compost them,or you will just dig them in again ..

Don't compost but, instead, offer the bulbs to neighbours, friends, family, work colleagues - even a help-yourself table by your gate.

Or add a little washing up liquid to your Roundup. It makes the stuff stick to the leaves so it gets absorbed for longer.

I've had the same problem. They are pretty but very, very invasive. I found it well nigh impossible to remove them all no matter what I did. It might be worth while asking at a local nursery or garden centre if they have any ideas. Whatever you do, once you dig them out, DON'T put them on your compost.

I have stopped trying to get rid of them. The flowers are very pretty and the leaves soon die off after flowering so now just enjoy them. The same applies to Chionodoxa bulbs.

Thanks for your advice.
Jan