Reading lists, references and footnotes sometimes contain Latin phrases and/or their corresponding abbreviations. Some common abbreviations and phrases which might be unfamiliar to you are explained below.
Et al. - An abbreviation for the Latin 'Et Alii ' which means 'and others'. This is often used when there are several authors for a book or article. The name of the first author is given followed by 'et al.' so that all the other authors' names don't have to be listed.
ibid. - An abbreviation for the Latin 'ibidem' which means 'in the same place'. When you see the word 'ibid.' in a reading list it is referring you to material in a source just mentioned. For example it could be another chapter of a book that has just been referred to. The abbreviation ibid. always refers to the immediately preceding reference or source.
Op. cit. - An abbreviation for the Latin 'opere citato' which means 'in the work cited'. This abbreviation is often used in footnotes combined with an author name and, sometimes, a date. It is referring you to a source, the details of which have already been given in full or which you will find in the bibliography. Whilst ibid refers to the reference that has just been mentioned, op. cit. usually refers to a reference which is earlier in the text or in the bibliography (i.e. not the one that has just been mentioned). The author's name and date will help you to identify the correct source.
Loc. cit. - An abbreviation for the Latin 'Loco citato' which means 'in the place cited'. It's use is similar to that of ibid. but not only does this phrase refer you to the same work just citied but also the same place in that work such as a page number or paragraph number. If Loc. cit is combined with an author name, it functions similarly to Op. cit. except that it is only used when referring to a full reference that states a specific place in a document such as a page number.
sic. - An abbreviation for the Latin 'sic erat scriptum' which means 'thus/such was it written'. This is often used after a quotation to show that the quotation is exact including reproducing any spelling or grammatical errors that occur in the original.