perspective of investigation. It is even possible to form immanent concepts for shared differences etween legal systems. I will show this advantage of immanent concepts in view of two different methods for protecting members against disinheritance: the first method is to secure a sum of money; the od is to limit the testamentary power by provisions which guarantee a certain share in the estate. The second method is that of the 'legal portion of the Civil The comparatist can limit his subject matter to the 'Pflichtteilsberechtigter'in German law and the Noterbe' in Austrian law. 'Pflichtteil 'in German law only creates an obligation to pay a substitute in money for the value of the share which an heir has in the heritage. The same is true for the Noterbe' in Austria. The comparatist can also limit his subject matter to the Pflichtteilsberechtigter' in Swiss law and the reservataire' in French law. The same german word Pflichtteil' means something else in Swiss law. in Swiss law the 'Pflichtteil is part of the heritage itself: it is not the value of a share in the heritage. In Switzerland the 'pflichtteil' is the guaranteed part of the heritage that is not at the disposal of the deceased Furthermore, the Swiss 'Pflichtteil'is equivalent to the French reserve, 1. e that part of the wealth of the deceased that is reserved fo certain heirs. (14)This example confirms two important statements: (1)terminological resemblance does not guarantee any conceptual correspondence fixing the comparability of the rules of different legal systems, a statement which has been elaborated in subsection 3. 1 above; (2 ible to look at similar ations that legal systems their national concepts. The second statement implies that Constantinesco is right in his assertion that Zweigert and Kotz's functional concepts are too broad and ill-defined. The formation of functional concepts pays only general attention to the intention of legal rules, e.g the intention of a part of a heritage to provide for the needs of certain heirs 4. Comparative concepts on the Internet 4. 1 The Index to Foreign Legal Periodicals The Index to Foreign Legal Periodicals is a bibliography which is available on the Internet. (15) The Index gives access to the contents of selected legal periodicals, excluding all types of source publications. The Index covers several countries, excluding the United States, the British Isles, the British Commonwealth, whose jurisdictions have a Common law basis. Nevertheless, the Index covers a large range, about 30 per cent, of Common law articles. The Index uses English keywords since the majority, about 70 per cent, of its subscribers are in Common law jurisdictions. (16) The editors of the Index to Foreign Legal Periodicals pretend to provide the researcher with an internationally acceptable legal terminology in English. However, the keywords of the Index to Foreign Legal Periodicals have been criticized. The English keywords of the Index evoke associations with Common law terminology since they follow, as far as possible, the keywords of the Index to Legal Periodicals covering Anglo-American periodicals only. As a consequence, the presentation of continental European law is more difficult than with, for example, Frenchperspective of investigation. It is even possible to form immanent concepts for shared differences between legal systems. I will show this advantage of immanent concepts in view of two different methods for protecting needy family members against disinheritance: the first method is to secure a sum of money; the second method is to limit the testamentary power by provisions which guarantee a certain share in the estate. The second method is that of the 'legal portion' of the Civil law. The comparatist can limit his subject matter to the 'Pflichtteilsberechtigter' in German law and the 'Noterbe' in Austrian law. 'Pflichtteil' in German law only creates an obligation to pay a substitute in money for the value of the share which an heir has in the heritage. The same is true for the 'Noterbe' in Austria. The comparatist can also limit his subject matter to the 'Pflichtteilsberechtigter' in Swiss law and the 'réservataire' in French law. The same German word 'Pflichtteil' means something else in Swiss law: in Swiss law the 'Pflichtteil' is part of the heritage itself; it is not the value of a share in the heritage. In Switzerland the 'Pflichtteil' is the guaranteed part of the heritage that is not at the disposal of the deceased. Furthermore, the Swiss 'Pflichtteil' is equivalent to the French 'réserve', i.e. that part of the wealth of the deceased that is reserved for certain heirs.(14) This example confirms two important statements: (1) terminological resemblance does not guarantee any conceptual correspondence fixing the comparability of the rules of different legal systems, a statement which has been elaborated in subsection 3.1 above; (2) immanent concepts make it possible to look at similar specifications that legal systems give to their national concepts. The second statement implies that Constantinesco is right in his assertion that Zweigert and Kötz's functional concepts are too broad and ill-defined. The formation of functional concepts pays only general attention to the intention of legal rules, e.g. the intention of a part of a heritage to provide for the needs of certain heirs. 4. Comparative concepts on the Internet 4.1 The Index to Foreign Legal Periodicals The Index to Foreign Legal Periodicals is a bibliography which is available on the Internet.(15) The Index gives access to the contents of selected legal periodicals, excluding all types of source publications. The Index covers several countries, excluding the United States, the British Isles, the British Commonwealth, whose jurisdictions have a Common law basis. Nevertheless, the Index covers a large range, about 30 per cent, of Common law articles. The Index uses English keywords since the majority, about 70 per cent, of its subscribers are in Common law jurisdictions.(16) The editors of the Index to Foreign Legal Periodicals pretend to provide the researcher with an internationally acceptable legal terminology in English. However, the keywords of the Index to Foreign Legal Periodicals have been criticized. The English keywords of the Index evoke associations with Common law terminology since they follow, as far as possible, the keywords of the Index to Legal Periodicals covering Anglo-American periodicals only. As a consequence, the presentation of continental European law is more difficult than with, for example, French