Her books were published by different companies, so getting in touch to ask them would be a problem. Another way might be to look her up on Abebooks. You'll find over 10,000 entries! By going through the listings and noting the earliest publishing date of each entry you'd arrive at the probable order of writing. But note that the order of publishing books may not correspond to the order of writing them, since a publisher may delay publication for some reason, allowing a later work to be published first. Good Luck!
http://www.abebooks.c...bt.x=91&bt.y=16&sts=t