Wikipedia article is correct, Russian for Dummies gives a simplification (which still works for the majority of nouns if you accept that -я is -ya so either [-'a] or [-ja], meaning -ь and -й are also covered).
That said, the go-to place for inflections is, of course, Zaliznyak's Grammatical dictionary (its rendering at English Wiktionary is actually quite fine and should be sufficient for most practical purposes).
Generally, there are three main options for accusative:
- a special, usually [u]-based ending - found in 1st declension singular (and in "pronominal declension" which is a mix of adjectival and substantive declensions) as -у [u]/-ю ['u/ju] and in adjectival feminine declension singular as -ую [uju]/-юю ['uju/juju]; outdated form самоё, originally for саму, would also belong here;
- always equal to the nominative - found in 3rd (feminine) declension (мышь) and in singular neuters except for pronoun оно (as well as, trivially, in indeclinable nouns like шимпанзе regardless of their gender and number); the exceptional masculine inanimate word путь (which shares most of its characteristics with 3rd declension, except for the instrumental) may be considered this or the next one;
- equal to the nominative if inanimate, to the genitive if animate - all declinable plurals (even neuters: accusative plural of an animate neuter чудовище is чудовищ, not чудовища), 2nd declension singular masculine (regardless of the specific ending: кон, конь, кий, змей, Валерий are all here), adjectival and pronominal declension singular masculine (aka all singular masculines except for 1st declension ones, which have the first option). To this category also belong кто - кого vs. что - что - the semantic split is by animacy although in terms of agreement, кто is masculine and что is neuter.
- a fourth option is very limited in its application: personal pronouns have accusative always equal to the genitive, regardless of animacy: in particular, accusative of он/она/оно/они is always его/её/его/их respectively (with an initial н- after a preposition but that's a different story), never он/она/оно/они.