Well done for wanting to research before committing yourself.
Here's my standard reply to this question.
The Testudo Horsfieldii, or Horsfield Tortoise which is commonly known as the Russian is the most northerly ranging tortoise in the wild. Other popular species are the Testudo Hermannii (Hermann) and the Testudo Graeca Graeca (Mediterranean Spur Thigh)
The Hermann is the smallest growing to about the size of a side plate and with a life span of around 60 yrs. The Horsfield & Spur Thigh will grow to around the size of a dinner plate and can live for around 120 years.
They are a hibernating species and are strictly herbivorous. They should be fed on weeds, weeds and more weeds. Dandelion, hawks beard, hawk bits, hedge mustard, prickly Ox tongue, greater plantain, clover, dead nettle, chicory, chickweed, sow thistle, vetch and common mallow are among the weeds which should constitute their entire diet. A little fruit, such as a small strawberry, can be given as a treat once every week or two. DO NOT give them root vegetables, legumes, excessive salad leaves, brassicas (kale, cabbage, sprouts, broccoli etc. These are high in oxalic acid, which prevents the absorption of much needed calcium.), spinach and, on no account, ever give them animal protein such as dog/cat food.... IT CAUSES SHELL DEFORMITY AND CAN KILL. You will also need a calcium and vitamin supplement.
Do not keep your tortoise in a tub, tank or vivarium, it must be kept on a tortoise table during the colder months, but is far better off out in the garden in natural sunlight, weather permitting. But beware, the Horsfield is an accomplished digger, so ensure your garden is tortoise proof or you make a tortoise proof enclosure.
While on the tortoise table you must supply a basking lamp and UV lamp or a combined lamp, such as the 'Megaray'.
You can download a comprehensive care sheet from the Tortoise Trust here; http://www.tortoisetrust.org/Downloads/T…
Another thing I must relate to you is this from my previous posts:
PLEASE, PLEASE find a reputable local breeder, or better still, get your tortoise from a re-homing service.
Sadly it is often the case that tortoises bought from pet shops are imported from former eastern block nations and claimed as 'captive bred' or 'farmed'. The truth of the matter is they are usually illegal wild caught Hermann, Spur Thigh, Marginated tortoises. Sadly, the Horsfield (Russian) is not yet protected by CITES, but at the rate they are being poached, they soon will be. They will not be examined by a vet or have their stools checked for parasites.
A vast number of these tortoises will die from stress and/or abominable treatment by the poachers and dealers. As few as 1 in 10 will actually make it as far as a pet shop and many of these will die within their first year in captivity.
See http://tortoise-protection-group.org.uk
This is not a problem confined to the UK or Europe, it is a worldwide problem.
While I understand and sympathise with people who buy from a pet shop, in the belief that they are freeing a poor unfortunate animal from 'Hell on Earth', your purchase serves only to fuel the trade. For the one tortoise you buy, perhaps another 9 will die for the pet shop to replace their stock.
ALWAYS check that a pet shop bought animal is certified as being bred in captivity in your own country, not an import.
I do hope you will follow my advice.
PUT AN END TO THE DEMISE OF THE WILD POPULATION AND THE MISERY OF THE TORTOISES POACHED FOR THE PET TRADE.