This is a tricky problem.

FORBES: Is A Family Member Ripping Off Your Aging Parent?

Experts and leading government agencies have been working on the space junk problem for decades, but it's a tricky one to solve, Schonberg told CNN.

CNN: STORY HIGHLIGHTS

But it struggled to agree on a valuation of Prodeco with Xstrata, and would presumably face the same problem with its other assets meaning a merger would be tricky to negotiate.

ECONOMIST: Xstrata and Glencore

Indeed, establishing a cause for Terence's blackouts has proved a tricky task for everyone, with highly qualified neurologists and cardiologists unable to say for certain just where his problem lies.

BBC: Heart monitor implant makes NI medical history